Subversion exists to be universally recognized and adopted as an open-source, centralized version control system characterized by its reliability as a safe haven for valuable data; the simplicity of its model and usage; and its ability to support the needs of a wide variety of users and projects, from individuals to large-scale enterprise operations.
Git Creator Linus Torvalds URL Maintainer Junio Hamano Users Linux kernel Ruby on Rails CakePHP Debian GNOME License GPL Documentation "terse", a lot of documentation for an unfamiliar system
Bazaar (bzr) Creator Martin Pool URL Maintainer Canonical Users Ubuntu MySQL Inkscape Squid License GPL Documentation Excellent! Aimed at beginners, UI designed to be intuitive
Mercurial (hg) Creator Matt Mackall URL Maintainer Matt Mackall Users Mozilla OpenOffice.org SymbianOS NetBeans License GPL Documentation Good, online book and command line help