A Vega 56 would be ideal, get it while you can & the price is low. That being said, before I had my V64 I played at 4K with an RX 480 with no real issues. In some games with the RX 480 you'll have to go down to 1800p (or drop render scale 10-20%), but you can keep most of the highest settings on. Basically, an RX 480/570 w/ 8GB offers you performance & visuals at least on par but in reality almost always better than what the best console currently offers (X1X), and this is usually because there's a lot of big visual gains that come for "free" (texture quality, ansiotropic filtering, etc). Any card better than those 2 is going to be even better. A V56 can get to almost double the performance of those two, so for the money it's a no brainer choice.