Snaps tend to install more cleanly due to including all of the dependencies independently of the host OS.
Snaps have a few drawbacks though, one being that they're very Ubuntu-centric. To my knowledge, the apparmor profiles which are using for sandboxing are currently not upstreamed, so app developers like the powershell devs recommend installing in "classic mode" which bypasses this benefit.
Snaps are also added to your $PATH, which can be a problem if a snap decides to use the same name as an application that was installed via package manager for example.
Also from what I remember, snaps are still heavily reliant on the Ubuntu app store. While it is possible to install an arbitrary .snap file, you can't add different repos.
Flatpak doesn't seem to have these limitations, being much more distro-agnostic and having a well-defined sandboxing mechanism. I recommend checking out Flathub if you want to give flatpaks a try.
-Josh