I use git because it's used by a few projects I follow, and also because git-svn works well and I need to interact with people who use SVN. Plus, git has branches that aren't copies, which are the way I am used to working. I also use repo.or.cz instead of GitHub, because I just need a mirror for open source software, not an overpriced pile of RoundRects.

That said, the various distributed VCs are more or less equivalent. Choose the one that's cheap, fast, and convenient to you.