KDE is the most fully featured Linux DE, and it's leaps and bounds above Windows's (WAY better file manager, better launcher, more features, and even less bugs somehow). The other day, my Windows 10's explorer.exe crashed when the file manager tried to load a directory, which is something that used to happen in Vista and hasn't happened in KDE for years IME.
Every default KDE install I've done comes with a default theme that is hideous and looks like it is designed by amateurs (I realize this is subjective, but it's also a fairly common complaint). However, I always hear people sing the praises of its stability. Is there a good theme/font/icon pack that you like that makes it look more polished without a lot of fussing on the end users' part?
But the DE, feature-wise, is so great compared to the others that it's like picking between a Volvo, a Model T, and several bicycles for my daily drive. The finish on the Volvo's dashboard is the least of my concerns; I'm just happy it's got AC.