Gitbox is my favorite. It’s simple to use and still has the most important features. Branching, merging, diffs, and history-of-a-single-file (awesome!!) are the things I use over and over. Just try it out, it’s free to use for 3 repositories and the full version costs $49 dollars.
The other app is Git-Tower, which has more features but also more UI to get in your way. I used the beta version but decided not to purchase 1.0 because it’s missing the one feature I can’t live without: ability to view the history of a single file.
I can’t live without source control and git is a tool I use daily. If you’re like me: lazy and hate the git command line, give one of these a try.