Lots of people will tell you to buy the LG - they are definitely awesome. Just a counterpoint:
I have a Sony XBR-65A9G, it's the same OLED panel as the LG TVs of the time (2019 - I think these were LG C8 series - two generations of LG TV ago) - LG is the only manufacturer of OLED panels so any OLED TV will have an LG panel. Sony TVs have a different (I think better, when I looked at them side-by-side) processing chip, a bit deeper blacks and a bit less jaggy on some interpolations, but the differences are pretty small. I primarily got this TV because for various reasons I can't have a center speaker in the location it's mounted - the TV panel itself is a speaker, you hook it up as the center channel of your receiver. Sound just "comes out of" the TV. If you have any situation like that where you can't have a soundbar/center channel that might be worth looking into.
The Sony TV is also an Android TV, whereas the LG sets (at least the ones I looked at in 2019) were still using the LG interface which was slightly different. I happen to prefer the Android TV but that's probably a coin flip for most people.
The XBR-77A9G still exists, for your family room size, it's the same as my TV just bigger, but the A9G line has been replaced in the other sizes (55/65) by the A80J line. A 77A9G should be on deep discount if you can find one.
The XR-65A80J is an OLED, has the acoustic surface and is on sale right now. There are also 55" and 77" versions.
The Sony A90J line is LED (not OLED) - it can be brighter, which matters if you watch mostly in a heavily-lit room, but otherwise the OLED sets are better
on contrast/black-level/viewing angle/response time.
Also, note that Samsung is likely coming with hybrid QD-OLED TVs early next year
EDIT: I should point out, this is probably the nicest single piece of technology I own. It's a beautiful TV. I was replacing a Pioneer Elite 50" plasma, considered the gold-standard at the time (2009? 2010?) for watching sports, and this TV is miles and miles nicer.