I start: Satisfactory - because having your production running 24/7 really makes this game even more enjoyable and satisfying. There are just docker container for the server out there.
What games do get better for you trough selfhosting the server?
For sure Minecraft Modpacks. Can set up factories for stuff you need and leave it running.
Terraria
That’s what I played, they already have been mentioned.
Would have loved it to have a Arma 2 Dayz Mod Server when it was on its peak. Get myself enough loot and raid other ppl on the official servers. But there were enough unprotected “hack” servers where you just could hack in your loot without getting banned. Oh Yea was a fun time. No, I never teleported ppl or nuked a whole server. I just got myself back what other hackers destroyed.
Assetto corsa with mods
Terraria, using Tshock.
How beefy does the server need to be for Satisfactory?
Valheim for sure. My friend and I tried two “Valheim hosts” and it was a nightmare to manage. 15 minutes later, our own server was up and running including V+ and we’ve had no issues since.