Earlier quoted context omitted.
Well linux have 10 main desktop managers that are under development right now. Each and every one of them does roughly 80% of what I want from a desktop. And I have uncomfortable experience on all.
Nonsense. There are, at best, a handful of desktop environments targeted at daily desktop users: Unity, KDE, Gnome-Shell, maybe LXDE/Razor if you're being generous. I've love to hear a single specific complaint about an experience you had with KDE that isn't "it was different from windows", especially given that it's the closest to the Windows daily interactions.
First - it is different than windows is absolutely valid complaint. Having to tweak muscle memory is highly unpleasant.
A single problem with KDE - windows key cannot be mapped to show the start menu without extension.
Second is that all the taskbars that I found for it were just worse than the windows one in multimonitor setup or ugly.
Also Alt+Tab worked inconsistently.