Sublime Merge is this but... sublime: https://www.sublimemerge.com/ it's amazing and pretty similar
That looks cool! Personally I love the simplicity of both Sublime Text and Merge so I gravitate towards those (I don't really care/need about customization)
I wish I liked it more but I've settled on fork now. Good you're happy with sublime. I'll check it out again once it's rounded off with more features
In the case of OP, Guitar looks a hell of a lot better on Linux installs. I suppose that's due to QT theming.
Smartgit works very well on Linux
I landed on it because the speed is unparalleled, but there's a few too many quirks (recent repositories never seems to work for me) and the UI is almost there but it's too hard to instantly see the status of things, particularly whether things are staged or not staged.