TBF I think I'm getting old and my eyesight is going anyway...
...I have a 55" 4k, and honestly, either it just has brilliant upscaling or my eyes are going bad, because I can't see any difference between upscaled 1080p and 4k unless I'm literally about 2 feet from the screen. From the couch, it makes zero difference
.
HDR is great though when the content supports it (most newer Netflix stuff does).