I’m using a 43" 4K LG TV (in PC mode - lower input lag and proper Chroma for text).
I think it looks fantastic in 2K but once I finally (if ever) can get a new GPU, I’d like to “try” and run in 4K.
Agree with DORRAGER - I keep render scale at 80 or higher. Definite drop off in my experience at 70 (for example - the leading edge of the A320 wing loses it’s chromy look and becomes pockmarked)
Personally, I like having the option to upscale my image when equipment permits but still having flexibility to go to 2K or even 1080P if required.
Good Luck!