I would not go near 4k on a PC monitor, if you have a 4k TV then you can run some older games on it, but as a PC monitor 3440x1440 is the best. Or 2560x1440 if you do not mind the smaller size.
I had a Samsung 4K moni and it was sweet but I am loving this Swift still but really tempted by a super wide 1440P in truth but buying a 1080 and a Rift means I will have to wait a while
