I've self-hosted first Owncloud from version 2.x, then moved to Nextcloud when it became clear that was the better option. Early versions could end up non-functional due to update glitches but for the last 3-4 years or so it has been mostly smooth sailing with here and there a glitch due to some app introducing a system-wide behavioural change - looking at you, Richdocuments/Nextcloud Office, stop adding headers to each and every app which cause things like Maps and News to stop functioning. Developing apps for it can sometimes be tedious due to frequent API deprecations which cause a lot of bitrot which in turn means you're own your own when it comes to less frequently updated apps.

It certainly is good enough for active use and, given a well-maintained collection of apps hardly takes any time to maintain. I'd say give it a go, it is free after all.