If you postponed reading about distributed version control systems hoping that somebody will just tell you which one is the best, then I guess that resource has become available: Distributed Version Control Systems: A Not-So-Quick Guide Through.
As for myself I have tried darcs a long time ago, then moved to Mercurial and successfully used it for a couple of my projects. I was quite happy with its SVN integration which sometimes is quite important if you are planning to use it with existing repositories for which migration is not an option.
Not so far ago, I have also installed Git on my Mac. I must confess that installing Git is probably the most difficult task (install xcode, install macports, use macports to download and compile all 20+ dependencies) and I would advise you to use this time to read the article!. However, I haven’t used it for long enough to have comments, but there is one feature that I really like: branching can be done in the same folder, so you don’t have to setup your environment for each idea you’d like to test.