@clacke I run Kallithea here because it is properly Free and it works with both mercurial and git (and I use both)
Closest to such a comparison I have found is this:
https://anarc.at/blog/2017-06-26-alioth-moving-pagure/
Pagure looks interesting too I think I will give it a look for my employer as an alternative to paying for the commercial edition of Gitlab