Super lightweight, super powerful, very Windowsy (but with enough customization that you can make it look however you want), the devs are very active in the community and have weekly blogposts documenting all of the new features and bugfixes.
They include tons of quality-of-life features I haven't seen elsewhere. For example, it prompts to make AppImages executable when you try to launch them if they aren't already (as opposed to having to dig around in the properties or chmod it from the terminal), and it does the same for .desktop files which GNOME requires running from the terminal. Applications like the Kate text editor use PolKit permissions, so you can just open any system file normally, edit it, and try to save it, and it'll ask you for your password (as opposed to most other text editors where you have to run the whole text editor as an admin to edit a system file).
This is also just a subjective thing, but I love how it looks. It has the best built-in dark theme I've seen, and even the default light theme is gorgeous. It feels incredibly refined, especially considering just how many features it has. Their "Simple by default, powerful when needed" tagline rings true for me.
KDE is fucking great tbh, shit is smooth, the theming is incredibly consistent across Qt and GTK, and it's just so easy to set it up however way you want it.
Windows? You got it. Mac? You got it. Tiling WM? You bet your ass.
I spent the longest time on KDE compared to other DEs but I've moved on to using just a window manager (i3-gaps rn). I would however 100% recommend it to anyone who wanted to use a DE. The only other good DE anyway is XFCE.
I judge my desktop environments on the basis of how nice they are when booted live. It's XFCE. Everyone needs XFCE.
I use Gnome, but I don't like it. But it has some nice properties that other DEs don't have. For instance, too many knobs and dials on KDE to get it right.
Mutter performs very nicely, and Wayland support is strong. It's whatever.
