Version control systems are important. No argue about that. At places where i used to work (and am currently working) i had the pleasure to meet three systems: cvs, perforce and subversion. All three have one important thing in common - they all suck. Well, some suck less than others (like subversion).
For my pet projects i decided to try these new kids on the block (read distributed version controls). I narrowed down to two: git and mercurial. I went for mercurial. Why? Well, first because it is written in Python and i have a thing for Python. I just love it. Second because bitbucket looks just nicer and cooler than github. And third … well, I think this guide by Joel Spolsky explains it much much better than i could do. Enjoy and be persuaded ;)