I've been around a couple version controlled shops and the best shop that I was in, for version control, used RCS. This was a shop that basically one developer worked on a piece of code @ a time, no branching necessary, but I believe that RCS can do this fairly easy if need be. It's simple & text based just to name the obivous features/benefits.
Simple in the commands are fairly intuitive from the command line on UNIX, and simple in the operation aspect.
Text based is a nice benefit, if for some reason the version should become corrupt it can be revived from the version control file.