Appimages are the only ones I ever bother with, and everything snap/flatpak related is removed as soon as possible. I spent enough time trying to debug the others to know they really arent worth the trouble.
I love AppImage, but unfortunately they seem to be generally ignored. Very few projects distribute AppImages and there doesn't seem to be any momentum behind their adoption.
A lot of project maintainers are very open to people porting their project to other distribution methods.
As long as you setup CI, it should be pretty self maintaining in most cases too.
No experience building AppImages but if it's something you can contribute to projects, that is the best way to see more of them in use. This is a big part of how a lot of apps got on flatpak.
