Scaling in Linux is a complete disaster. It's already buggy with integer based scaling and totally broken with fractional scaling.
I also like the scaling in Windows best, in theory. It's buggy and support by many apps is still not there. Beside that I would always take the 27" 5K screen over a 4K one, just because it's visibly sharper
What environment are you talking about? I run KDE Plasma on X11 and fractional scaling is ok.
More importantly, text quality on Linux is identical at 175% to 200%.
Have you ever compared 27" 5K to 27" 4K side-by-side?