Gitlab.com used to be slightly less available than GitHub but recently I think the tables have turned and Gitlab saas is relatively stable.

I also enjoy Gitlab as a platform. It's got everything, good board, good repo, good issues, good CI, extremely good registries. It's got the equivalent of gists and pages... It a better product all things considered.

GitHub just wins because of popularity. It's WordPress all over again, the thing people use because it's a thing people use.