My favourite VCS is Mercurial. Before that I used SVN, and I have no regrets about it. But it's still popular, and from time to time I have to use SVN. Here is solution how you can work with SVN from Mercurial. I didn't tried it myself yet, but will certanly try it then time comes.
Updated 02.05.2012. So, the need has come early, and I tested it. It works! I'm almost sure it's buggy to work flawlessly with advanced reps, but if you need to just grab some repo it's definetely enough.