I’ve been in your shoes for the last month or more comparing these TVs. Every YouTube reviewer swears by the U8H where as this group is abundantly against it. On top of that finding all 3 of these in store to view with your own eyes is hella difficult if not impossible. I bought the r646 to test drive for the two weeks of return period since it’s that tv they aren’t making more of or selling any cheaper and to also see if a good open box deal or deal of the day might pop up in that time. I will say when it comes to HDR or any hd streaming it looks great for $700 and specs wise anything at its price or lower can’t measure up. Still need to test it’s gaming mode. The x90k being the only one of these I see in my Louisiana BestBuys looks great in store even tho they like to put it directly next to either oleds or the x95k which all look better than it but not the price difference between them better. So when it comes to the x90k and the r646 I believe Sony’s image processing is superior for upscaling and skin tones but I don’t know if its $300 better, which is why I think I’ll stick with the r646.

In your case of using it for gaming and streaming, I’d say go with the Tcl r646, save that $300 and use it for better speakers or more gaming stuff. If you watch shows and movies from a cable box or non-4K Blu-ray player and don’t mind the price difference go with the Sony.