Powerful gitk/gitg alternative?

SmartGit is an alternative. It works on Windows, Mac OS and Linux:

http://www.syntevo.com/smartgit/

I don't think this question really has its place here, but if you want recommendations, I can link you to Fork or SourceTree if you're on Windows or Mac, or GitExtensions if you're on Windows.

Edit : As it seems like people are still looking at that answer, I can now also recommend GitKraken.