The way I see it, 27 inch 1080p needs a good bit of AA.
27 inch 1440p doesn't need AA, or very little anyway.
But at 120 or 144hz on a fast moving game, you will hardly notice anyway, unless you are standing still admiring the graphics or taking screen shots.
I see no point in 4k resolution unless you are running over 30 inches on your desktop screen, or if using it in your living room, you are using a projector and getting a screen 80 or 100 inches accross. I don't understand why there is such enthusiasm for it, especially seeing the PC magazines posting screen shots.
Is it some sort of dick measuring contest? Are they just trying to justify tri-sli GTX Titans? Maybe I'm just out of the loop and the big trend in PC gaming at the moment is to play with a joypad whiles't sitting on your couch with the whole family in front of a display that fills an entire wall, rather than the idea I had in my head that we were all huddled over a keyboard in darkened rooms under the stairs, attics and cellars?
I used a 40inch 1080p screen on my desktop for years. It was okay, a bit more resolution would have helped certainly but the immersion was good.