I use a self hosted gitea instance. Haven't had any issues with it, i can highly recommend it. Not super useful if you want contributions though xD
Sourcehut. I like how they approach things there, and am happy to pay for my account to support them.
I would guess that GitLab is the most used one right after GitHub, but I may be incorrect.
I still like Gitlab a lot and use it wherever I can. I think that it was once talked about very favorably on HN, but it seems to have lost its popularity after its IPO (or even earlier).
There’s also the swath of non-Git DVCS options like Fossil, Mercurial, darcs, Pijul, et. al. and they have their own forge hosting options.
sourcehut - the hacker's forge
Self-hosted Gitea.
Closed source. I can't see the point of publishing anything innovative if it is just going to be vacuumed up by some giant corporation and sold back out to users at $10 a month.
Codeberg seems like a decent host for Free Software projects. There is also Sourceforge, but I don't know if people have already forgiven and forgotten the mistakes made in the past.