Comparisons
Where this fits, and where it does not
Each of these says plainly what the alternative does better. A comparison page that only flatters its own product tells you nothing you can use.
ReviewOS and GitHub
The default, and what you give up or gain by leaving it.
ReviewOS and GitLab
A whole DevOps platform, against a forge that does one thing.
ReviewOS and Forgejo
Two self-hosted forges with different centres of gravity.
Still deciding?
Mirror one busy repository and review a week of real work in it. That answers more than any table.