I haven’t looked much into the differences, but from my brief research, it appears that Forgejo has just recently updated such that migration from Gitea is no longer possible. I knew that they had become a “hard” fork last year but it has now diverged.

From a feature standpoint, I know that Forgejo is working on Fediverse integration. Beyond that, I think the differences are less apparent.

So to answer your question, I use Gitea and have for a long time. They’ll still remain MIT-licensed even if it’s no longer fully open source. However, the owning company can (and may) cease open source development. If I had known of Forgejo breaking away earlier, or if I were a new user, I would have probably started with Forgejo. That’s my recommendation.