I'm on both networks and we actually use both at work and we are paid users
The current idea is to use bitbucket for the in-house private source repos
and github for the open source projects.
I don't have a strong preference for either one, because I think git is
suck in general.
I was a long time fan of http://darcs.net , but I didn't have the chance to
use it recently.
I have to admit though that the lack of proper interactive commit tool for
darcs puts it behind git, no matter how crap git is otherwise. :(
It really makes me sad but I'm not skilled enough to write such a tool...
The equivalent of github in darcs land is http://hub.darcs.net which looks
very simple but quite powerful actually and u can host it yourself too.
There is http://fossil-scm.org too which has a lot of nice aspects, like
size, built-in wiki, etc, but there is no equivalent of github for it as
far as I know.
These last 2 are closer to the spirit of picolisp's minimalis, that's why I
thought it's worth mentioning them.