I used to maintain here a list of all the free software version control systems I knew anything about, with comments about some of them. While there is still experimentation in open source version control systems, at least for now we appear to have settled on some standards: Git, primarily, and sometimes Mercurial. My thoughts on which to choose for your project are already given in the section called “Choosing a Version Control System”, and it's not sustainable for me to maintain an increasingly out-of-date list of other version control systems that you are unlikely to use anyway. If you want a list, though, https://en.wikipedia.org/wiki/List_of_revision_control_software is a good place to start.