Which code versioning system?

Git, Bazaar, Subversion...

Back at Amazon in 2000 we used CVS. It was the first time I'd ever used a command line version control system. I stayed with CVS as my versioning system of choice until 2005 when I started using Subversion on a contract. Aside from the fact that I had to alias the word "cvs" to "svn" because I kept mistyping, I decided that I really liked svn better.

But now I'm wondering about other systems. I have friends who swear by the offline branching of Git. And some of the open source projects I really like use Bazaar for their version control. But I've never used either of those myself.

So, tell me, what is your favorite open source version control system and why?