I have been advised to try RCS, CVS, SVN or something of this nature.

Of those three I would definately go for Subversion.

What do you use?

Subversion :-)

Are you happy that you use it?

Yup. I didn't realise what a royal PITA CVS was until I'd used subversion for a few months. It took that long for my CVS brainwashing to expire.

Are you happy that you use it? What do you wish you could use?

I'm pretty happy, and don't feel the need to change at the moment. If I was having to maintain some public repositories I would probably look at something like darcs, monotone or svk since I like being able to commit when I don't have connectivity.