Gogs is a visual clone of the Github graphic design, functions, menu structure, in short, just about everything from Github. SO sure, it works well and looks good, but uh.. its a total copy. Meanwhile Gitea has forked Gogs, as noted extensively very recently.

Regarding Kallithea, I installed and used it for work. I like Kallithea, although the features and interface are not as well developed as some alternatives discussed here.

Kallithea is far more lightweight to setup and admin that Gitlab, but not as full-featured as Gitea, which I recommend to anyone who asks.