Hey,
first of all, don't even buy a Threadripper for gaming, it's no use and it is too overpowered. But for gaming you'd be better off going with a normal Ryzen from the 5000 series, if you look for the best performance, go for the 5950X or 5900X, with a Threadripper you literally just lose FPS. When you are also planning to use it as a serious workstation, then you can go for the Threadripper.
As for motherboards I think Asus has the best ones. But please do not buy a Threadripper for gaming, it is no good. The Threadripper is made for workstation and/or server purposes.
If you want the best of the best performance in the graphics card section, I would suggest going with a 6900 XT, a 3080 Ti or 3090.
Kind regards