I have used both CVS and SVN a *bit*, but certainly not enough to profess to be an expert with either, nor to be in a position to strongly recommend one over the other.

However, given that one of the main goals of the Subversion project was to "write a new version control system from scratch, retaining the basic ideas of CVS, but without the bugs and misfeatures.", you would have to assume that SVN is probably a better choice. Assuming of course, that those original goals have been realised :)

Cheers,
Darren :)