Cinnamon is the only other desktop environment that I can really use besides KDE. To me they’re equal in quality. Cinnamon does some things better than KDE, KDE does some things better than Cinnamon. It varies based on how each one is configured in your distro’s repository more than anything. KDE on Arch is top notch. Cinnamon on Arch is hot garbage. Cinnamon on Ubuntu is usually really good, KDE on Ubuntu was barely usable last time I tried it.
If you know a lot about desktop environments you could fix either one yourself but I only use them based on which one works better after I download it and configure basic settings.