As for where appimages are most useful, it's mostly for applications that are similarly updated rapidly where the distro packages don't keep up. An example is PS1/PS2 emulators. Flatpaks could fill this void but the developers are providing appimages, not flatpaks.
I've only had to use an AppImage once or twice since all the applications that I want to use through Flatpak are available on Flathub.
As for where appimages are most useful, it's mostly for applications that are similarly updated rapidly where the distro packages don't keep up. An example is PS1/PS2 emulators. Flatpaks could fill this void but the developers are providing appimages, not flatpaks.
It doesn't really matter if you are running a rolling release distribution but Flatpaks, Snaps and AppImages doe have their place. I like to use Flatpaks for proprietary applications because then they are sandboxed even though the sandbox ain't perfect and for applications that require 32 bit libs on your system.
Another benefit of appimages is that you can make a folder with the same name as an appimage with .home in the name. So name.appimage and name.appimage.home. That way whatever files and folders would have ended up in your home folder instead end up in that folder instead. So your app becomes "portable" from one computer to another.
I prefer using a command-line tool to install my packages, Flatpak being similar to using the normal package manager.
Want to transfer the emulators and games you rarely play to an old computer attached to a tv? Only takes a move command. Want to delete your entire Heroic library with no trace left behind? Done. Nice not having to remove shader caches and other stuff afterwards.
I don't play emulator games behind in front of my tv, if I play an emulator I do it at my desk and now days it's even possible to stream games from your desktop to your tv. I keep my Games library for Steam and Lutris in separate location, easy enough to remove the whole library without complications.
The lack of menu integration is whatever for me, it takes what, 20 seconds to make your own menu item? Worth the hassle for the other benefits.
It takes more than 20 seconds because last time I did it took me 5 minutes because then I want to find the perfect icon for a menu item as well
I did forget that distributions like Mint have packages that are outdated but yeah good to use Flatpaks, AppImages or Snaps for those applications. Lastly I wasn't trying to start a Flatpak vs Snaps vs AppImages discussion or argument, I was just stating what I use myself and you are too
but you don't have to convince me of anything. I tend to use them in these order:
1. Packages from the default repos.
2. If they aren't available from the repos I use Flatpaks.
3. If they aren't available from Flathub I use an AppImage.
4. If they aren't available as AppImage I use the AUR.
5. If it's a proprietary application I use a Flatpak or Appimage.
6. If it's an application that requires 32 bit libraries I use a Flatpak or AppImage.
7. I avoid Snaps.
