In the scope of the post this might be minor but: why not GitLab? Both GitHub and GitLab have their problems (e.g. barring contributors from certain countries), but at least the latter is open source and could be patched or become self-hosted if the need arises.
GHC chose a similar path also for this reason (Why not GitHub? — «Github is not open-source, so we can’t fix any (future) issue we might have with it»).