NV or AMD gfx for 4k?

[Dan Irwin]

So my 2013 dell can't quite drive my new 4k display. It's missing DP1.2 on
the onboard intel gfx.

(Well, actually, I can get it into 4k mode by toying with xrandr, but it
won't drive a second sub-hd display i have laying about)

I am personally leaning towards nvidia, because it's worked so well in the
past on linux. Like 10+ years ago...

What is the current state of play? Who has the most stable drivers, either
proprietary or in kernel?

Thanks.

Dan.