Which Bitbucket GIT desktop client should I use for Windows 7?

There are a couple of options - both are free and are standalone GUIs SourceTree from Atlassian  https://www.sourcetreeapp.com/download/ TortoiseGit https://tortoisegit.org/ Hope that helps!

SourceTree from Atlassian [ https://www.atlassian.com/software/sourcetree/overview/   ] GitKraken [http://www.gitkraken.com/ ] If you really want to learn GIT correctly go with the command line first. 

Try this one: http://www.sourcetreeapp.com/ It's made from Atlassian itself

I love https://www.sourcetreeapp.com/download/ from Atlassian. But this is my personal opinion. The main down side is that every user in a company needs a personal account.There is an old Player: https://tortoisegit.org/. But I’m not a fan of this tool. There are to much points to see that it comes from TortoiseSVN and it feels more like SVN over Git…https://www.syntevo.com/smartgit/ is a Client with a longer history. It’s a client with a lot of features. But it’s not free for commercial projects.A new client is http://www.gitkraken.com/. It is one of the youngest tool Git GUI. (Started Nov 2015) So, there will be some points, but it has some great features and a lot of keyboard shortcuts. And the main benefit: It runs on all major systems: Windows, OSX and Linux.And: There is the official Git GUI client. But… don’t try it ;-)There are some others, visit https://git-scm.com/downloads/guis for more information.

The Source Tree team is thrilled to announce the latest addition to our family Atlassian distributed https://www.atlassian.com/git/tutorials/what-is-version-control/system (DVCS) family – http://sourcetreeapp.com/.For some time now many Windows developers have been requesting a native counterpart to the Source Tree Mac desktop client. Windows developers, say goodbye to the command line and use the full capabilities of Git through SourceTree’s beautifully simple interface (and stop being jealous of what your Mac friends are using).