After trying out Cosmic, Gnome,KDE Plasma, and Hyprland, I feel like plasma is the most usable for me coming from Windows. It solves the gripes I had about lack of customizability while still starting me off with a familiar homebar. I will be going back and forth with gnome for a while.
I really like gnome and the sliding desktops, and all the extensions seem to make it very customizable as well, but not directly like plasma, instead you mix and match (or make) extensions to get the look you want. (correct me if im wrong, I used it for a day)
Hyprland seems very nice for multitasking but the keyboard focus of the presets ive tried doesn’t really appeal to me, I like being able to just use my mouse sometimes.
Cosmic, is definitely an alpha and im interested to see what it becomes, wont be using it now.
KDE has given me the desktop I need for the past few years. Hyprland isn’t a desktop environment, as far as I know.
Before KDE I used Cinnamon on Linux Mint. It was functional, but after many years I wanted a change.
Use whatever suits your needs. In my experience, KDE and Cinnamon are the most complete desktop environments without having to install extensions or extra software. Both are mature, have large communities behind them, and release incremental updates frequently. Those are my criteria for a good desktop environment.
Trying cinnamon right now, Its definitely functional, closer to windows back when I liked it. Feels boring, but in a good for productivity way.