Here's what we've tried so far:
Nextcloud: I'm running a nextcloud instance since ~2 years (it's awesome) and tried nextcloud talk several times, though for some reason we could not get audio and or video to work.
Just this week we tried jitsi because it's open source and can be self-hosted. Unfortunately while it worked in principle jitsi uses large amounts of cpu cycles when running in the browser and additionally latency and video quality was an issue.
For us the best option as of now is still https://whereby.com which works well regarding stability, audio/video quality and latency, though it's not self-hosted. I'm not affiliated in any way with them, I just like their product.
I'd love nextcloud talk to work, and I'm very curious about other solutions I'm not aware of - self-hosted and otherwise.
Edit:
After reviewing my nextcloud talk setup I saw that I didn't set up a TURN server which might be the reason it's not working. So it's not nextcloud, but incomplete setup.