Mercurial

Read the docs and hang out on the lists and you'll see a world of difference. Of course, trying it out for yourself makes it pretty clear, too. :-)

We use Git. It's been great so far but it is a bit complex if you're not used to DSCM. The amount of commands that you really use in day to day development is very, very small however. I haven't tried Mercurial myself but a friend of mine uses it. There's also monotone to try out. For those researching SCM tools and want to move away from the horrible Subversion, start with these links:

http://en.wikipedia.org/wiki/Monotone_%28software%29 http://en.wikipedia.org/wiki/Mercurial_%28software%29 http://en.wikipedia.org/wiki/Git_%28software%29

I watched Linus's google talk, and he says that mercurial is the only other scm that he finds respectable. For obvious reasons, he still prefers git.

I'd say any system that allows easy branching and merging will make experimenting with your code much more fun.