Which is better for a bright living room?

The Sony. Its QD-OLED panel reaches higher brightness and holds color better in daylight. The Panasonic is fine in a dim room but washes out more in strong light.

Is the bigger Panasonic worth choosing over the Sony?

If your seating is more than about 8 feet away, yes. The extra 10 inches makes more difference than the panel upgrade at that distance.

Which has better smart TV apps?

The Sony. Google TV has the widest app selection and smoother updates. Panasonic's platform covers the main streaming apps but has fewer niche ones.

Which is better for gaming?

The Sony. It pairs HDMI 2.1 with VRR and low input lag on current consoles. Check the specific Panasonic model for HDMI 2.1 support before buying for a PS5 or Xbox.

Both OLED types have similar panel lifespans for normal viewing. The Sony's newer panel and processing are the safer bet for a long ownership, but neither has a clear durability edge.

Panasonic 65-inch OLED TV vs Sony Bravia 8 II 55-Inch QD-OLED TV

Buy the Sony if you want a newer, brighter QD-OLED with Google TV and a smaller footprint. Buy the Panasonic if you want a bigger 65-inch picture and its well-regarded picture tuning. The Sony's QD-OLED panel generally beats the Panasonic's standard OLED on color volume and brightness, and owners praise its processing. The Panasonic gives you 10 more inches of screen for a similar class of TV, which matters more in a large room.

Choose the Panasonic 65-inch OLED TV if you sit far from the screen or want the largest picture in this comparison.
Choose the Sony Bravia 8 if you want the latest QD-OLED panel, Google TV apps and a brighter image in a bright room.

Prices

Panasonic 65-inch OLED TV: $2,299.99 at Amazon (last seen Nov 10)
Sony Bravia 8 II 55-Inch QD-OLED TV: $2,299.99 at Newegg (last seen Nov 9)
Difference: both cost the same at the latest prices (Nov 9 and Nov 10)