Git - Git is a free and open source version control system designed to handle everything from small to very large projects with speed and efficiency. It is easy to learn and lightweight with lighting fast performance that outclasses competitors.
TortoiseSVN - The coolest interface to (Sub)version control
GitKraken - The intuitive, fast, and beautiful cross-platform Git client.
uberSVN - Free, easy to implement UI for Subversion which includes:
Mercurial SCM - Mercurial is a free, distributed source control management tool.
kdeSVN - Comfortable graphical SVN client for linux.