I first started using source control when I was a student. I started with rcs. I had also read about sccs, but rcs was free and it was available. I liked having a history of changes and the ability to get at old versions of files, though I didn't fully appreciate its value at the time. A while later, I started using cvs on projects worked on by 2-4 people. This was where CVSROOT was on the filesystem.

Then, I took a job that used Microsoft Visual SourceSafe. It had its advantages and disadvantages compared to cvs. I disliked the interface, though. From time to time, I tried to figure out how to use it from the command line, but never really got anywhere.

A while later, the source control got switched to cvs (client-server). I really liked that change. Mainly because I could then do away with having to work on Microsoft Windows at all.

Where I work now uses perforce, which I like. It's a modern source control system with a command-line interface, and there's a nice emacs package for it that I also use often.

I imagine other modern source control systems are pretty much like perforce, but the most I've ever done with them is to download source code from public subversion repositories. I've also played with GNU arch a little, but with just a local repository. It was like going back to rcs, in a sense.