The LG OLED C8 is a great 4k OLED TV with excellent picture quality. The emissive technology allows it to produce perfect blacks, which is excellent for dark rooms. The image also remains accurate when viewed at an angle, which is great for those with wide seating. It performs well with HDR content, as it can produce very bright and saturated highlights. The motion handling and input lag are also excellent, so it feels very responsive to gamers or PC users. It isn't perfect though, as the brightness changes depending on the screen content and static images shouldn't be shown for long on the TV due to temporary image retention and the risk of burn-in.
Excellent TV for a wide range of usages. The LG 55C8PUA has perfect blacks, resulting in excellent dark room performance. The TV handles motion extremely well due to the instantaneous response time and ability to flicker the image at 60Hz to clear up motion. The picture also remains accurate at an angle, which is great for those with wide seating. Reflection handling is excellent for rooms with lights or glare on the screen.
Excellent choice for watching movies in a dark room. Perfect blacks result in deep and detailed dark scenes. The TV can display most content without judder, but some stutter is visible due to the low frame rate of movies - especially for wide panning shots.
Great choice for watching TV in a bright room. Reflection handling is excellent, which is great for rooms with lights or glare on the screen. The TV also has a good brightness to overcome ambient light. The WebOS smart platform works well for casual browsing or watching content on Netflix. For regular watchers of channels with a lot of static content, there may be a risk of burn-in though (see here).
Excellent for sports fans. Motion handling is excellent due to the instantaneous response time and ability to flicker the image to clear up motion. Dirty screen effect is also not an issue, as the screen is very uniform. Picture quality is also excellent, and remains accurate when viewed at an angle which is great for large numbers of people to watch an important game.
Excellent TV for gamers. Input lag is very low, so the TV feels very responsive. Motion handling is excellent due to the instantaneous response time and ability to flicker the image to clear up motion. Picture quality is also excellent due to the perfect blacks.
Excellent for watching HDR movies in a dark room. Picture quality is excellent due to the perfect blacks and impressive uniformity. The LG 55C8 can produce very bright highlights in real scenes and also produces saturated colors, to make HDR pop. The fast response time does result in some stutter, especially when viewing movies in long panning shots.
Impressive HDR gaming performance. Input lag is very low, so the TV feels responsive with HDR. Motion handling is excellent due to the instantaneous response time and ability to flicker the image and clear up motion. Picture quality is also excellent, and the TV can make HDR scenes pop due to the high peak brightness of highlights and ability to produce very deep colors. For people who play games with a lot of static content there may be a risk of burn-in though (see here).
Great choice for PC use. Image remains accurate when viewed at an angle so the sides of the screen are uniform. Supports chroma 4:4:4 for clear text across all backgrounds. Also, the LG C8P supports a 1080p @ 120Hz input for those who want the most fluid experience. Motion handling is excellent, due to the instantaneous response time. Unfortunately the brightness of the screen changes depending on the content and areas of static content may have a risk of burn-in (see here)
The design of the LG 2018 C8 is excellent. The stand is wide but very sturdy and well built. The frame around the screen and stand are made of aluminum and seem well built. The stand is designed to help direct sound throughout the room, but due to its shape, it is not possible to place a soundbar directly in front of the TV. The TV is more uniform in color (black and dark gray) compared to the black and white design of the B7. Similar to other LG OLED TVs we have reviewed, there is only basic cable management.
The stand is wider than last year's C7, this time taking up nearly the full width of the TV, so it may be hard to fit on some tables. It supports the TV well and is very sturdy. It is made of aluminum with a hard plastic finish.
Footprint of the 55" TV stand: 35.0" x 9.2"
The rear of the LG C8PUA is very similar to the C7. Basic cable management, only a small removable cable guide as seen here. The 4 HDMI inputs face to the side, but the composite input is rear facing and may be difficult to access if the TV is wall mounted. The controls are located on the back to the side, similar to the C7.
The borders of the LG OLED C8 are very thin and look very good. There is almost no gap between the border and the first row of pixels.
The top half of the screen is exceptionally thin, comparable to last year's C7. The bottom half houses the electronics and is thin and it sits flush to a wall when mounted
The overall build quality is excellent. The TV is solid and there were no obvious build issues or gaps. Care should be taken when moving the TV as the top is very thin.
The LG OLED C8 is an OLED panel, and as such has an infinite contrast ratio since individual pixels can be turned off. This results in perfect blacks when viewed in a dark room, great for Horror or Sci-Fi fans.
There is no need for local dimming on an OLED screen like the C8, as there is no backlight. This video is for reference only.
Good SDR peak brightness on the LG OLED C8, almost identical to last year's C7. Real scene brightness is bright enough for most rooms. Highlights do not stand out in SDR. The TV remains consistent at ~350 cd/m² except when showing a large bright scene, like our 100% test window, where the screen dims significantly due to the Automatic Brightness Limiter(ABL).
With an 'OLED Light' setting of 40 or less, the fluctuations between scenes due to ABL drops to 20 cd/m² or less.
Update 05/04/2018: The brightness window tests were retested using our Samsung K8500 Blu-ray player, rather than from a PC as originally published. This was done to keep the test results consistent with the 2017 TVs, because they were all tested using the Blu-ray player. The C8 measures a little brighter from the Blu-ray player, but not majorly.
Update 11/27/2018: We retested with the latest firmware and found that, while the HDR brightness remained generally unchanged, the SDR brightness decreased by 50 cd/m² in all but the 100% window which remained unchanged. Results found above are updated.
Good HDR Peak Brightness, slightly brighter than last year's E7P and much brighter than Sony's A1E, especially when showing small highlights. Real scene HDR Brightness is very good, but still short of the 1000-4000 cd/m² HDR is mastered for. Large bright scenes are very dim due to the Automatic Brightness Limiter(ABL).
Update 11/27/2018: We retested with the latest firmware and found that the HDR brightness remained generally unchanged. Results found above are updated.
Excellent gray uniformity on the C8. There are some very faint vertical lines visible on our 50% test, these are mostly visible in very dark uniform scenes. Only slight dirty screen effect in the center, which is good for watching sports.
Update 04/27/2018: When the TV shows very dark gray shades, like our 5% gray uniformity test, vertical and sometimes horizontal bands are very visible across the screen. This was also an issue with all 2017 and 2016 OLED TVs we tested, including the Sony A1E. It shouldn't be an issue in most normal content, but in some very dark scenes it can be visible.
Very good viewing angle on the LG C8PUA, as is typical of OLED screens. Black levels remain perfect regardless of viewing angle. Colors shift when viewing off access, but the shift is not as severe as other TVs like the Samsung Q8C. This TV is a great fit for a large room with side seating.
The OLED55C8PUA has perfect black uniformity, with no clouding due to its ability to turn off black pixels. This TV is especially well suited to watching movies in a dark room.
The OLED C8 has excellent reflection handling. The glossy screen results in very defined reflections, but at a very low intensity. The anti-reflective coating gives reflections a purple tint, similar to other high-end TVs like the E7 and Q8C. The results are excellent and there should be no issues using this TV in a bright room.
The most accurate results before calibration were on the 'Expert (Dark Room)' picture mode, with the Gamma setting changed to 2.2. Out of the box, the color accuracy and white balance are good, although the temperature is a bit warm so the colors are shifted a bit yellow.
Excellent color and white balance dE after calibration, better than the C7 and Samsung's Q9F. While the calibration out of the box was already very good, after calibration the colors were nearly perfect. Gamma follows our target almost perfectly.
You can see our recommended settings here
The C8 upscales older 480p content well. The resulting image quality is not overly sharp.
The LG OLED C8 upscales 1080p content played from a Blu-ray or game console well. There were no obvious issues.
With WRGB OLEDs all four subpixels are never on at the same time, so we have two photos.
Alternative pixel picture.
Excellent coverage of the P3 color space, nearly identical to the C7 and E7 from 2017.
The HDR EOTF in the 'Technicolor Expert' picture mode follows our target PQ curve very well until it rolls off at the TV's peak brightness. The EOTF in 'PC' and in 'Game' are very similar to that of 'Technicolor Expert', although 'Game' is brighter than the other two.
When displaying HDR content in 'PC Mode' colors appear washed, the C8PUA does not detect the wide color gamut and the setting cannot be changed.
Update 05/02/2018: The color gamut was erroneously measured at a 50% stimulus. It has been remeasured at 75% stimulus to be in line with our other TVs. The results remain almost identical.
Update 11/27/2018: We retested with the latest firmware update (04.10.06), and the PC Mode issue has been corrected.
Decent color volume, similar to last year's C7 and B7A, but much worse than the Samsung QLEDs. The C8 has decent coverage of the P3 color space, but is unable to produce overly bright, saturated colors. This will be noticeable in bright outdoor scenes when watching Movies or TV Shows.
The LG OLED C8 displays our test gradient smoothly with no significant banding. In certain scenes there is some banding noticeable in large areas of similar color. This can be reduced by enabling 'MPEG Noise Reduction', which toggles the gradient smoothing feature of the C8. This reduces the visible banding but also results in a loss of fine detail.
The TV shows some signs of image retention even after 4 minutes of recovery time.
This test is only indicative of short term image retention and not the permanent burn-in that may occur with a longer exposure to static images. We are currently running a test to help us better understand permanent burn-in. You can read about our investigation into this here.
Note: There is some variation between panels even of the same model. Some panels may be more or less prone to image retention.
Update 11/01/2019: Updated text to include our stance on burn-in.
Although we don't expect most people who watch varied content to have any issues, OLED TVs, such as the LG OLED C8 do have the possibility of experiencing burn in.
The LG C8 has three features to help mitigate burn-in. We recommend enabling the 'Pixel Refresh' and 'Screen Shift' options and setting 'Logo Luminance Adjustment' to 'Low'
You can read about our investigation into this here
Like all OLED TVs, the response time is nearly perfect. There is some slight overshoot when transitioning from a black frame, such as in the 0-20% and 0-80% transition, but this should not be noticeable. The response time is excellent when watching fast-paced movies or sports, as the TV has no ghosting/movement trails during fast motion.
The LG OLED C8 has an optional BFI mode to help reduce blur. This is new this year for LG OLEDs, although Sony did implement it on last year's A1E. On the C8 this is enabled by setting 'Motion Pro' to 'On'. With 120 fps content the C8 drops every other frame.
The TV uses motion interpolation (commonly known as the Soap Opera Effect) to artificially increase the frame rate of lower fps content up to a much smoother 120 fps. Motion Interpolation can look strange to many people, and it creates artifacts. In scenes with a lot of motion, the C8 stops interpolating the extra frames to avoid creating artifacts, preferring accuracy over smooth motion.
To enable this feature when watching lower frame rate content, set 'TrueMotion' to 'User' and adjust the 'De-Judder' slider for low frame rate content (such as 30 fps), and the 'De-Blur' sliders for 60 fps content.
The C8, like all OLED TVs, has a near instantaneous response time. This results in each frame remaining static for nearly 40ms when watching 24 fps content which creates noticeable stutter. The stutter can be reduced by enabling motion interpolation to increase the frame rate.
Update 05/13/2019: The settings required to remove Judder have changed. We've updated our text below.
Update 05/10/2018: We retested 24p playback on the C8 with firmware version 04.10.05, and it is now able to remove Judder from all sources, except when BFI is enabled(Motion Pro set to 'On').
The TV is consistently able to remove judder from native 24 fps content, whether that content is played from the native apps or external sources such as a Blu-ray player. It can also remove judder consistently from 60 fps content.
To enable this feature when playing 24p content from an external player, the 'Real Cinema' option must be turned on. Previously, it was required to set the TruMotion sliders to '0' as well.
The LG C8PU does not support any of the variable refresh rates technologies such as G-Sync, FreeSync, or the native VRR which will be available in HDMI 2.1.
Very good low input lag, similar to the C7P. In game mode, the input lag is very low regardless of resolution, and outside of game mode the input lag is lower at 4k than the C7, and is one of the lowest we have ever tested.
The input lag was slightly higher in 4k @ 60 Hz + HDR. This result is highly unusual and has been retested to verify the results. The input lag is still low, and should feel very responsive.
Update 11/27/2018: We retested with the latest firmware update (04.10.06) and found two previous bugs had been fixed. Now 4k in HDR has the same input lag as in SDR and 4k @ 60Hz @ 4:4:4 + 8 bit HDR is properly being displayed and has been measured.
Most of the common input resolutions are displayed properly without any issues. The TV does not support 1440p resolution. When connecting to a PC, the HDMI input must have its icon changed to 'PC'. 4k @ 60 Hz @ 4:2:2 or 4:4:4 color is only supported when 'HDMI ULTRA HD Deep Color' is enabled in the 'Picture/Additional Settings/' menu for the chosen input.
The new α9 processor also supports 120 fps files in 1080p when played from a USB drive.
Update 11/27/2018: We retested with the latest firmware update (04.10.06) and 4k @ 60Hz @ 4:4:4 + 8 bit HDR is now displayed properly.
The C8 does not have a component input. It does support composite input via the included adapter. Surprisingly, the TV has 3 USB 2.0 ports, and no 3.0 ports unlike the 2017 C7.
Like the 2017 OLEDs, the OLED C8 does not have an analog audio output. To connect a wireless headphones you will need a digital to analog converter like this one.
Update 02/27/2019: While the TV doesn't support Atmos passthrough via a Dolby TrueHD carrier signal (common in Blu-ray disks), it is advertised as supporting Atmos passthrough via Dolby Digital Plus, which is the Atmos format used by some sources like Netflix; our testing confirmed this passthrough on the LG C8.
The LG C8 has an above-average frequency response. The LFE (low-frequency extension) is at 64Hz, which is also above-average and much improved over last year's model, the C7. This means that the bass won't be able to produce any thump or rumble, but it'll have a decent amount of punch and body to it. The frequency response above the TV's LFE is well-balanced, and it has a self-calibrating system, but this doesn't completely correct the modes of our test room (the bumps between 200Hz and 300Hz). Additionally, this TV does pretty loud, and doesn't produce too much pumping and compression artifacts under maximum load.
The C8 has a decent distortion performance. The THD response is rather elevated, which is typical of most TVs and doesn't increase too much under maximum load either.
The webOS interface is split into three sections: settings, inputs and apps. The menus are more responsive than last year. A new quick access button has been added in the top right for easy access to the search function. The interface is easy to use and fast to navigate, but first time users may find it confusing.
The C8 did not display ads during our testing, but there is an option in the menu for advertising cookies so the TV may have ads at some point or in certain regions.
Update 04/27/2018: We have received reports of Ads in the C8 app store, at least in Russia.
Update 7/12/2018: We have found ads on other 2018 LG TVs as shown here, so we assume all 2018 LG TVs have ads. The score has been updated to reflect this.
Like the rest of LG's lineup, the C8 comes preloaded with most of the most popular apps, including Netflix, Amazon Video, and YouTube.
The remote itself is nearly identical physically to last year's C7. It has a limited selection of controls, allowing control of basic functions and quick access to the settings and search menus. When pointed at the TV the remote acts as a pointer, which when combined with the scroll wheel found in the center of the directional pad allows quick access to all options.
Voice control is now much better, on par with Samsung's service, and allows you to control other LG devices powered by ThinQ, including lights, air conditioners, etc... The TV will also be compatible with Amazon Alexa and Google Home later in the year. The basic commands we tried worked very well, and allowed us to search YouTube, switch inputs, change some settings, and even ask about the weather. In order to use voice control features (known as ThinQ AI) you must consent to sharing your viewing information and voice information, since the TV offloads certain requests to an external service. We don't know what exactly is shared with LG so if you are concerned about privacy, this should be left disabled.
Like almost all LG TVs and monitors, the C8 has a single rocker joystick on the back of the TV. It works very well and allows quick access to most functions of the TV.
We tested the 55" model (OLED55C8PUA). For the most part, we expect our review to be valid for the 65" (OLED65C8PUA) and 77" model (OLED77C8PUA).
If someone comes across a different type of panel or if their LG OLED 55C8PUA doesn't correspond to our review, let us know and we will update the review. Note that due to variances between panels some results such as gray uniformity and image retention may vary between individual units.
|Size||US Model||EU Model|
Update 12/11/2018: We have received a few notes that the 77'' model makes a hissing sound. If you experience this, we suggest that you contact LG.
The LG C8P offers excellent performance across the board. However, it isn't perfect and comes at a high price. Check out some of our comparisons below for different recommendations depending on your usage. See also our recommendations for the best flatscreen TVs and the best OLED TVs.
The LG C9 and LG C8 OLED are extremely similar overall. The C9 we tested had less temporary image retention, but this varies between units, and might not be indicative of the full lineup. The biggest difference between these TVs is the inputs. The C9 has 4 HDMI 2.1 inputs, which for the moment, doesn't add much if anything at all. Once there are HDMI 2.1 sources, the C9 should support a 4k @ 120 Hz input, even at full chroma. The C9 also supports eARC and supports the HDMI 2.1 variable refresh rate technology, which is currently only supported by the Xbox One.
The LG C2 OLED is a lot better than the LG C8 OLED. There's not much difference in picture quality - they both display deep, uniform blacks in a dark room with no blooming around bright objects. The C2 is a lot brighter, though, especially in HDR, so bright highlights stand out much better. The C2 also has more advanced gaming features, including variable refresh rate support to reduce screen-tearing.
The LG G2 OLED is a lot better than the LG C8 OLED. There's not much difference in picture quality - they both display perfect inky blacks with perfect uniformity in a dark room. The G2 is a lot brighter, though, especially in HDR, and bright highlights stand out much better. The G2 also has more advanced gaming features, including variable refresh rate support. On the other hand, the C8 is a bit more versatile, as it includes a stand, whereas the G2 doesn't come with a stand, as it's designed to be wall-mounted.
The LG C8 OLED and the LG CX OLED are very similar TVs. Their OLED panels allow them to individually turn off pixels, resulting in an infinite contrast ratio and perfect black uniformity. Picture quality between each are similar, and the real differences are that the CX has HDMI 2.1 support, allowing it to support 4k @ 120Hz. It also has VRR support to reduce screen tearing, which the C8 doesn't have.
The LG C8 is a bit better than the LG C7. While the overall performance of the two is very similar, the LG C8 has an optional Black Frame Insertion feature that the C7 lacks. This feature can improve the perceived clarity of motion on the C8 at the expense of some brightness.
The LG C8 is very similar to the LG B8 for mixed usage. The C8 offers performance in the same ballpark, and the small differences between the two TVs could be due to panel variance. The C8 has the newer Alpha 9 processor, whereas the B8 still carries the Alpha 7 processor, but we did not see a significant difference in performance.
The LG B9 OLED and LG C8 OLED are very similar. The B9 has no signs of temporary image retention, but this varies between units. The B9 is also more future proof at it has 4 HDMI 2.1 inputs, supports eARC, and supports the HDMI Forum variable refresh rate technology, which is great for nearly tear-free gaming.
The LG C8 is somewhat better than the LG B7A. While the overall performance of the two is very similar, the LG C8 has an optional Black Frame Insertion feature that the B7A doesn't have. This feature helps to improve the perceived clarity of motion on the C8, at the expense of some brightness.
The LG C8 is slightly better than the LG E7P. The LG C8 has a black frame insertion (BFI) feature that can help clear up blur in fast-moving content. Also, the LG C8 can get brighter, which matters if you watch a lot of TV shows in a bright room. On the other hand, the LG E7P has a dedicated soundbar and somewhat better input lag when playing HDR games and can remove 24p judder from any source.
These are two different types of TVs, each with their advantages and disadvantages. The LG C8 OLED is an OLED TV that can individually turn off pixels to produce perfect blacks. The OLED also has wider viewing angles and an almost instantaneous response time that delivers crisp motion. The Samsung Q70/Q70R QLED doesn't have the permanent burn-in risk and can get brighter, so it's more suitable for a bright room. The Samsung is packed with gaming features like FreeSync support, which is great for more serious gamers.
The LG C8 and the LG E8 both have very similar performance. The LG E8 has somewhat better sound quality due to the embedded soundbar. The two TVs, however, differ significantly in design, as the E8 has a more elegant style whereas the C8 has a more classical one.
The LG C8 is significantly better than the Samsung Q6FN. The LG C8 is an OLED TV with perfect blacks which has remarkable picture quality that looks amazing in a dark room. The LG C8 has better reflection handling and wider viewing angles, and is more suitable for a wide room with many light sources. On the other hand, the VA panel of the Samsung Q6FN doesn't have a permanent burn-in risk, like the OLEDs, and the TV incorporates the FreeSync variable refresh rate and a low input lag, which is great you're a fan of video games.
The Sony X950G and the LG C8 use different panel technologies, each with their own strengths and weaknesses. The C8, which is an OLED TV, delivers perfect, uniform blacks, great for dark room viewing, and it has wide viewing angles. Unfortunately, the C8 also has a chance of permanent burn-in. The X950G doesn't look quite as good in a dark room, but doesn't have any risk of burn-in.
The LG C8 is slightly better than the Sony A1E. The LG C8 has better input lag that makes it more responsive and better SDR peak brightness that makes it better for TV shows and sports, which are usually viewed in brighter rooms. The Sony A1E, on the other hand, has better support for the 1440p @ 60Hz signal which can be important for video gaming.
The LG C8 is better than the Samsung Q8FN, unless the possibility of burn-in with an OLED TV concerns you. The C8 delivers perfect dark room performance with perfect blacks, as well as much wider viewing angles great for a large seating area, as well as perfect black uniformity and near-instantaneous response time. This comes at a cost, as the OLED panel is prone to temporary image retention and permanent burn-in. The Samsung Q8FN is brighter and doesn't experience image retention.
The LG C8 is slightly better than the Sony A8F. While the overall picture quality and performance are very similar, the LG C8 has lower input lag, which is great for gamers. The C8 also has a better smart interface that is faster and easier to use.
The LG C8 is significantly better than the LG SK9500. The LG C8 has perfect blacks, which is great if you watch movies or HDR content in a dark room and better viewing angles to accommodate wide seating arrangements. The LG C8 also has better reflection handling so you can place it a bright room and a faster response time which is great for fast action. On the other hand, the LG SK9500 has a lower input lag for video games and doesn't have the permanent burn-in risk.
There are only minor differences between the LG C8 and the Sony A9F. The C8 is a bit brighter than the A9F, but the C8 has worse color volume. We don't know if this is a result of variance between panels. The C8 runs LG's WebOS smart interface, whereas the A9F runs Android TV OS. Both are great, but they have vastly different interfaces and some people may prefer one over the other.
The LG C8 OLED is slightly better than the Sony A9G OLED. The C8 can get a little brighter in SDR, which is important if you watch TV shows or sports in a brighter room, and it also has lower input lag, which is great for gamers. The Sony A9G has a less aggressive Automatic Brightness Limiter (ABL), which is important if you watch movies in a dark room.
The LG C8 is significantly better than the Sony X900F. The LG C8, like all OLED TVs, is suitable for a large room with a wide seating arrangement. It also has perfect blacks, making it ideal for dark room viewing conditions. The LG C8 has an instantaneous response time which leaves a very small blur trail in fast-moving content like sports, and a lower input lag which is great for gamers. The Sony X900F, on the other hand, has a VA panel that doesn't have the permanent burn-in risk of the OLEDs and can get brighter.
These are two different types of TVs, each with their advantages and disadvantages. The LG C8 is an OLED TV with perfect blacks, outstanding dark room performance, and wider viewing angles. The C8 has a slightly better response time and better gray uniformity that help to deliver a better sports performance. The Samsung Q80R doesn't have a permanent burn-in risk and can get brighter in SDR, so it's more suitable for a brighter room. Finally, the Q80R is packed with gaming features, like FreeSync support, that are an attraction to serious gamers.
The LG C8 is much better than the Samsung NU8000. The LG C8 has perfect blacks that improve the picture quality significantly in a dark room. Also, the LG C8 has better reflection handling and better viewing angles and is suitable for a large room with many windows. On the other hand, the Samsung NU8000 doesn't have a risk of permanent burn-in, can get the whole screen brighter, and has lower input lag. It also supports the FreeSync implementation of the variable refresh rate, which is excellent if you play video games.
The LG C8 is much better than the Samsung NU7100. The LG C8 is an OLED TV with perfect blacks and good viewing angles that make it a better choice for most usages but especially for watching movies in a dark room. Also, the C8 has better reflection handling and a much faster response time that allows only a small blur trail to be visible in fast content. The Samsung NU7100, on the other hand, has a VA panel that shows no signs of permanent burn-in risk and a lower input lag both in SDR and in HDR, and this great if you play video games.
The LG C8 is much better than the Samsung Q7FN. The LG C8 has perfect blacks due to its emissive OLED technology, and this improves picture quality and looks great in a dark room. It has better viewing angles and better reflection handling so you can move around while watching your favorite TV show. The Samsung Q7FN, on the other hand, can get much brighter and can fight bright room glare better. Because of its VA panel, it doesn't have the risk of permanent burn-in. Finally, the Samsung Q7FN has a lower input lag and is very responsive if you play video games.
The LG C8 OLED TV is better than the Samsung Q9FN for most people, unless you watch a lot of static content and are concerned about burn-in. The LG C8 has an infinite contrast ratio and no need for a local dimming feature, as well as an ultra-wide viewing angle, but it can experience permanent burn-in. The C8 has a nearly instantaneous response time, although this can bother some people as 24p content can appear to stutter. The Samsung Q9FN has much better color volume and is much brighter and better capable of overcoming glare in a bright room.
The LG C8 OLED and the Samsung Q60/Q60R QLED are two different types of TVs, each with their advantages and disadvantages. The LG is an OLED TV that delivers perfect blacks thanks to its emissive technology. It has wide viewing angles and almost instantaneous response time for a very crisp motion. The Q60R doesn't have the permanent burn-in risk and can get brighter is SDR, so it's more suitable for a bright room. The Q60R also has nice gaming features like FreeSync support and low input lag with motion interpolation.
The LG C8 is much better than the Vizio P Series 2018. The LG C8, just like all OLEDs, has perfect blacks and good viewing angles which make it a better choice if you enjoy watching movies in a dark room, or if you have a wide seating arrangement. The LG C8 can also handle reflections better if your room has many light sources. If you are a sports fan, you'll appreciate that the C8's faster response time leaves just a small blur trail in fast action. The Vizio P Series 2018, on the other hand, is brighter, has a lower input lag which is great for games and has a VA panel that shows no signs of permanent burn-in risk.
These two TVs are different types, each with its advantages and disadvantages. The LG C8 is an excellent OLED TV with outstanding dark room performance thanks to its perfect blacks and excellent viewing angles. On the other hand, the Samsung Q90/Q90R QLED is a remarkable TV with excellent dark room performance that doesn't have the risk of permanent burn-in and is packed with gaming goodies.
The LG C8 is a bit better than the Vizio P Series Quantum, unless your main usage is in a bright room. The C8 has even better dark room performance than the already excellent Vizio Quantum, with true perfect blacks. The C8 also has much wider viewing angles, great for a wide seating area. The Vizio P Series Quantum is much better for a bright room, as it's significantly brighter with SDR and HDR content. The Quantum also doesn't have a risk of burn-in with static content.
The LG C8 OLED TV is much better than the 2017 Samsung Q9F. The LG C8 has perfect dark room performance thanks to the infinite contrast and perfect black uniformity, as well as the perfect local dimming feature. The C8 has a much wider viewing angle and excellent gray uniformity, great for sports fans with wide seating areas. As an OLED panel, the LG C8 is susceptible to image retention and burn-in. The Samsung Q9F doesn't have the risk of burn-in as it's a VA panel.
The LG C8 is significantly better than the Samsung Q8C, unless the possibility of burn-in is a concern for you. The LG C8 has an OLED panel which delivers a perfect dark room experience, and has very good viewing angles, although there is the risk of temporary image retention or permanent burn-in. The LG C8 has better motion handling, as the OLED pixels have a near-instantaneous response time. The Samsung Q8C doesn't have any risk of burn-in.