Which is better for gaming?

The LG G5. Its 165Hz refresh rate, VRR and four HDMI ports beat the Samsung's ALLM-only listing.

Which has the better picture?

The LG's OLED evo panel with anti-glare coating edges out the Samsung on brightness and reflections. The Samsung's 77-inch size makes more impact in a large room.

Which is better for a bright living room?

The LG G5, because of its glare-free coating. The Samsung does not claim anti-glare treatment.

Does the Samsung have better sound?

Yes. The Samsung lists Dolby Atmos, while the LG does not specify its audio setup.

Is the step up to the Samsung worth it?

Only if screen size matters most. You gain 22 inches and Atmos sound but give up the LG's faster panel and anti-glare.

LG G5 Series OLED evo 4K TV (55") vs Samsung QN77S85F 77" OLED TV

The LG G5 is the better TV for most people. It is a 55-inch OLED evo panel with a 165Hz refresh rate, four HDMI ports, Wi-Fi 6E and a strong anti-glare coating, so it suits gaming and bright rooms. The Samsung S85F is a 77-inch OLED with Dolby Atmos, HDR10+ and SmartThings, and it wins on sheer screen size and built-in sound. Reviewers rate the Samsung highly, but the LG's brighter evo panel and faster panel give it the edge on picture and motion.

Choose the LG G5 if you sit close, game at high frame rates, or need a screen that fights reflections in a bright room.
Choose the Samsung S85F if you want the biggest picture for a large room and value built-in Dolby Atmos sound and SmartThings.

Prices

Samsung QN77S85F 77" OLED TV: $1,697.99 at Walmart (last seen Nov 9)