I switched to Debian and have been happy with it. The release cycle is less frequent than Ubuntu Desktop, which means fewer disruptions, and Debian Backports make it easy to pick new versions of the important stuff. Flatpak is also available on Debian.

Linux Mint is widely praised for being basically Ubuntu without the worst Canonicalisms (such as Snap). They maintain a Debian edition in parallel to their main one, as an exit strategy in case Ubuntu ever becomes unsuitable for their base. Some people already use that as their daily driver.

Just in case you're not aware, the default desktop environment on whatever distro you pick doesn't have to be what you use. I switched to KDE Plasma when Gtk-based desktops became intolerable, and haven't looked back.