There's things I don't like about it, and there are a looot of long-standing open issues, but I think GitLab is definitely better than GitHub in a number of ways. My org uses both (and also Azure DevOps, joy) and my team expects that the trend will be migrating from GitLab to GitHub. There are a bunch of things for me to grieve in that, much to my own surprise.
We use a self-hosted GitLab for about 6 years now. The only thing that is really awful is if your MR gets too big. Then GitLab will simply stop showing any code changes above a certain line threshold.
