Mercurial is a much better fit for how my mind works than Git (I feel that Git is from the school that thrives despite complexity, where I prefer the school that puts lots of effort into a really clean model to minimize complexity).
But I am now giving up on Mercurial: every open source project I play with is on github, so I absolutely need to master Git - and I don't want to keep using two systems.
The network effect wins.