Either should work fine to be honest, don't let not using Debian before put you off - if you install it with Gnome its basically the same as Ubuntu, if you're using CLI only - its essentially exactly the same.

If you're literally running as a home server - VM on Windows is fine as long as the host is on when you need it, that said RPi4 is good and I've got two at home running various containers - but then maybe you wanna do other things with it. :-)