mosh is for interactive sessions, to keep them working when the connection is flaky.

autossh is for keeping unattended ssh tunnels alive, if the connection is flaky or one end is only intermittently available. So for using tunnels for the sort of thing you might otherwise use a VPN for.

AIK, for using mosh, you need to install mosh on target host as well. Seems like autossh doesn't need this step.

I have used autossh + tmux before to enable X forwarding (just for clipboard sharing). Couldn't do that in mosh.

Biggest issue i have with mosh is that it you cant scroll up the history. It is kind of a deal breaker for me.

hence why most throw in tmux/screen on the other end, possibly automatically so:

https://github.com/blinksh/blink/discussions/1526