What are some alternatives?
When comparing TortoiseGit and Git Extensions, you can also consider the following products
GitKraken - The intuitive, fast, and beautiful cross-platform Git client.
SmartGit - SmartGit is a front-end for the distributed version control system Git and runs on Windows, Mac OS...
SourceTree - Mac and Windows client for Mercurial and Git.
GitHub Desktop - GitHub Desktop is a seamless way to contribute to projects on GitHub and GitHub Enterprise.
git-cola - git-cola is a powerful GUI for git, a distributed revision control system.
gitg - gitg is a git repository viewer targeting gtk+/GNOME.