Gerrit is the gold standard of code reviews and I'll die on that hill. I've heard many a good things about phabricator too, but it requires lot of special tooling while gerrit just uses plain old git semantics.

That said, I live git-pr so far. I have a forgejo instance and I like it for what it provides, but without federation, external contributors aren't able to contribute.

If git-pr can be made to work with forgejo, I'll just go for it (self hosted, of course).