I don't really use Plasma itself (and soon i wont even be able to if the rumors of them dropping X11 support are to be believed) but i do use various KDE apps, like Krita (which i use for most painting stuff), Kate (my main programming editor, coupled with clangd for C/C++ programming), KolourPaint, Spectacle, Ghostwriter, etc and in general i find KDE/Qt apps to be more to my liking in their UX than anything based on Gtk (or at least Gtk3-or-later, Gtk2 stuff is for the most part fine).