GitHub for Mac
I am a long time user of GitX(L). My only use case for a GUI is to build up commits. I find it much easier to click on lines to add to a commit than to use the command line utilities.
Other than that one use case I am a big fan of just using the command line.
Instead of GitX (L) I am giving GitHub for Mac a try. The selecting of lines to commit seems a bit smoother.