My experience with 4k has essentially been that it's too small for the display sizes I want to have on my desk - and the fractional scaling support is always quite a bit of work to get right (as evidenced by this post).
I've found that 2k (2560x) displays at 27" give me great real estate without any need to scale.
1440p at 27" with no scaling is perfect for my desktop. I wish it were more popular, because it's a great compromise between quality and performance for gaming.
The relatively common use of "2k" to mean 2560x1440 has always struck me as confusing though, since it's not half as wide as 4k.
Words mean whatever people agree they mean, but I feel like "2k" is too ambiguous.
I've found that 2k (2560x) displays at 27" give me great real estate without any need to scale.