Yep was one of those Gnome KDE bashers until I tried it.
As for me way to remember window positions & size as have dual displays with 3 workspaces.
So this is critical for my workflow. And KDE is the only one that does this out of the box.
Tag On having widgets in panel or desktop. As was always installing screenlets in gnome. As like to have basic Weather,Calendar,Time on Desktop. KDE makes it easier to add what is already built-in without the need to keep installing extra this and extra that.
Built it smooth compiz desktop effects no extra work involved. Outstanding Dolphin file manager. Built in separate wallpaper for dual displays, Fully configurable Applications & System notifications,Full keyboard & mouse keys assignment, And an overwhelming set of tweaking for themes.
With the others always found this missing or that you have to install something else that may or may not work right in a given DE.
With KDE everything is there. And if I don't need it then just ignore it and use what I need that KDE delivers out of the box.