Which is better for gaming?

The LG G5. Its 165Hz panel and VRR support handle high frame rates better than the Samsung's 100Hz panel, and it has four HDMI ports for consoles and a PC.

Which is better in a bright room?

The LG G5. LG rates its Brightness Booster up to 45% brighter than earlier evo panels and adds a glare and reflection free coating. The Samsung has anti-glare too, but a standard OLED panel.

Is the Samsung worth stepping up to over the LG?

Only if you need a smaller 48-inch screen or want Alexa built in. Otherwise the LG offers more screen, a faster panel and newer wireless.

Both are OLED panels with similar lifespans. The Samsung has a longer track record with 854 owner ratings at 4.8 out of 5; the LG is too new for that kind of history.

Do both support Netflix and Disney+?

Yes. Both are smart TVs with Netflix and Disney+ listed, plus YouTube on the Samsung.

Which has better voice control?

The Samsung S90F, which supports Amazon Alexa. The LG relies on LG ThinQ AI and does not list Alexa support.

LG G5 OLED evo 4K Smart TV (55") vs Samsung S90F 48-Inch OLED TV

The LG G5 is the stronger TV: a 55-inch OLED evo panel with a 165Hz refresh rate, Wi-Fi 6E, four HDMI ports and a brightness booster that LG rates up to 45% brighter than earlier evo panels. The Samsung S90F is a 48-inch OLED with a 100Hz panel, Alexa built in and a 4.8/5 rating from 854 owners, but it gives up screen size and refresh rate. Buy the LG for a bright room, big-screen movies and high-frame-rate gaming; buy the Samsung if 48 inches fits your wall and you want Alexa on board.

Choose the LG G5 if you want the larger 55-inch picture, a 165Hz panel for fast gaming and Wi-Fi 6E.
Choose the Samsung S90F if 48 inches suits your space and you want Alexa built in and a proven owner rating.

Prices

LG G5 OLED evo 4K Smart TV (55"): $1,599.99 at Amazon (last seen Nov 7)