For AppImages specifically, the guy that made the tech has had a lot of controversial arguments and opinions and a general unwillingness to accept change. Things like intentionally making it so Wayland doesn't work because he dislikes Wayland. Also dropped a PR for AppImages for things like OBS but then refused to take responsibility for making sure all the features works and maintaining it, and then throwing a fuss when the OBS maintainers ultimately decided to not move forward with it due to lack of support commitment. Dude wanted to throw all the burden on the OBS team and then proceeded of accusing them to be paid by RedHat to favor Flatpaks. Also got mad that distros stopped shipping some outdated/unmaintained libraries AppImages relies on and refuses to upgrade it. Just massive ego problems overall around his pet project that it AppImages.

• https://github.com/obsproject/obs-studio/pull/2868
• https://gist.github.com/probonopd/9feb7c20257af5dd915e3a9f2d1f2277
• https://gist.github.com/probonopd/3de4f97598d89df627690bbe4f8c402c

Think of AppImage like a standalone executable on windows, you download it, it just works and thats good. But it doesnt get automatic updates and to get a new feature you need to download it again. Flatpaks and Snaps don't have this issue and are more like traditional package managers.

One of the big benefits is there are plugins for the app stores on various distros. So it makes it just simpler. For me there are flatpaks for what i use and easy to find.

Imho flatpaks have better integrations with menus etc

I like appimages personally.Find them useful when i have conflict of depencies in package manager.I don't like snaps comparing to flatpak.Flatpak let u add custom repositories but not snaps ,canonical want to control from where u will install snap apps.