As a long-time Windows user, things like settings or notifications are laid out much more logically, as well as I feel like everything in KDE is just a little better integrated than Gnome. Also a lot faster for me to get it to a point where I feel like I like it, and it seems to use a lot less system resources (although it's been a couple years since I daily'd linux, so it's possible that's different on Gnome these days).

But otherwise I don't have a whole lot of specifics, it just feels a lot more mature in general, like I don't have to search for anything I need DE-wise, it's always right where I'd expect and extremely well-built. And any extra functionality from add-ins works nicely.