I've tried Cosmic recently and it's glitches galore right now (on nvidia at least). I think safest point is KDE. The most familiar paradigm, mature wayland support with mixed refresh rate displays, HDR and other modern features that XFCE can't do.
After ~10 years of using XFCE, I recently for the first time encountered flickering, after an NVidia driver update. I disabled compositing and it went away. Still happy, but clearly something broke there. Pretty sure someone's trying to fix it, somewhere.