The BEST is the one made by Apple, the £4,000 ish one XDR display....
Then everything else is like your preference. like the Apple Studio display plays well with the Mac, people say it gives the best TEXT pixel to pixel DPI clarity. I am using a Huewei 28" Mateview that is 4k+ res and not even using it at max res (it is too small) and it looks fine. I guess it depends on personal preference but I do not, DO NOT at all notice any blur on text, zero. Not one bit. There is also the Acer 5k one for like £700 or so.
My 2nd screen is a 16" 3k OLED monitor. Due to the small size, it has the same DPI has Apple's 5k display, like 221 DPI. and compared to the Huewei, clarity is the same to me.
I think the whole 5k thing is over blown personally, 4k monitor is fine, I bet 99% of users don't use an Apple display with their Mac mini/Studio.