If you want a good test try doing text editing on 1080p vs. 4k at whatever distance on whatever TV. For me, text is always easily visibly nicer on the 4K. Your PC is not doing any video compression, so you can be sure that everything is pixel perfect in both resolutions, and truly a fair comparison.
I recently bought a gaming laptop and decided to go with a 1080 screen because it had gsync for smoother graphics versus a 3k screen. My main monitor and work machine are retina displays.
Definitely had a bit of shock reading text on the 1080 screen. My eyes had forgotten how painful it was by comparison.
