I find AppImage files quite annoying, I must admit. I understand that it's annoying packaging for all the different Linux distros, but this doesn't feel like the solution. Maybe renaming them and dumping them in /usr/local/bin would make them integrate better with the OS, but I usually just avoid them.

Flatpak has been quite nice when I've used it, if a bit more awkward to figure out first time.

Snap is fine, but the actual publishing side of it I found quite confusing and arduous when I tried it, so from a developer point-of-view I would probably avoid it (unless it improved a lot in the last year).