KDE and Qt apps (since Qt is so superior to GTK in almost every way) are superior to anything you find in Windows. Compare Windows's Explorer, the file manager, to Dolphin. The next best FM is PCManFM, which switched from GTK to Qt. Nautilus (now GNOME Files), which is still GTK, is a comical toy by comparison.
The GNOME desktop looks very nice and has high polish but is very feature limited. Here's a feature that might interest gamers: KDE lets you disable desktop composition, which makes your desktop (including games) much smoother, but you lose DE animations and transparency effects. Try it and then drag some windows around on a high-refresh screen, on and then off, to sense the difference. In fact, the smoothness you'll feel is how smooth the Windows 10 DE is by default (it pains me to note). This difference is also felt in games. Fullscreen games are supposed to disable composition on most DEs, but whether they actually do this is unknown and I don't think they do at all if you keep your games windowed (which I do since some Proton games, like Fallout 4, work way better in windowed mode, and it's easier to access stuff on neighboring monitors without Alt-tabbing). I don't think you have any control over composition in GNOME, and conversations with GNOME devs on this topic made it seem like they see no reason at all to not have composition in current year and that a DE without composition is broken in their eyes.