> I wonder why no one is trying to create a killer Git client on Windows.
I'd bet the majority of Windows developers use Microsoft technologies, preferring TFS over Git. While there are less Mac users, they're all your target market.
I am aware of SourceTree. However, I personally don't find it a killer client. I prefer SmartGit over SourceTree. Don't get me wrong, the app is functional but it doesn't have the features I want in a client. E.g. one of the most important feature for me is the Folder View for my repository where I can quickly look up any file and see history for it.
You get this (or something like it) in the OS X version of SourceTree: a tree view of your working copy, plus the Reveal Log... context menu option. So if you were going to switch to OS X anyway, purely over the git client situation, once you've spent £1,500 on your shiny new Mac you will at least not have to spend any more on the git client.
(I don't know why the Windows incarnation lacks a tree view. A Win32 treeview would be perfectly functional, and they're easy to code for. (Never having seen the SourceTree code, I can of course confidently say that this would apply here.) But if you don't mind a flat list, Reveal Log... is present and correct. So you'd be good to go already.)
http://www.youtube.com/watch?v=cyyuqf1m-2E
For a moment, it made me want to ditch Windows and migrate to Mac just to use this client.
Personal favorite, being able to see up stream commits without actually applying them on your local branch.
I currently use SmartGIT on Windows and I am sort-of-happy with it. I wonder why no one is trying to create a killer Git client on Windows.