@skorpio11x I myself play on a high end computer with dual 4K monitor. I think I wouldn't recomand it to everyone.
Mostly because everyone who uses my computer just tells me "this is wayyy tooo smalll how can you read that?" And no I don't want to change the settings to have everything bigger because that's the point of 4K basically...
And also because 4K is still biased because of the speed of the cables available on the market.
Which means even though your computer can produce a lot of FPS, your monitor will only receive a few because of the cable. Also, depending on the type of player that you are, you will want to maximize the refresh rate of your monitor, and affordable 4K monitor aren't going above 60Hz at the moment.
So with my experience, I would suggest you to stay on 1920x1080 or so, and maximize the FPS/Refresh rate of your monitor on maximum settings (and a 1070 should do if you go with Nvidia and is far less expensive than her big sisters the 1080/1080ti)
Staf'