We wanted to switch to Git from Mercurial because we wanted something like Gitlab. The only reason we didn't was that there wasn't any app for Git which was as user-friendly as TortoiseHg.
We considered switching to Git as well for a similar reason (GitLab). However we discovered Phabricator provides similar toolset at GitLab and also supports Mercurial. It's open source - you can run a local instance (no cost but also no support) or pay for them to host. They also recently started a free plan where they will host an instance with up to 5 users.
1. Check out Gogs (Github clone written in Go). Gitlab is quite heavy, we would've needed an extra machine to run it, so we tried Gogs and absolutely love it.
2. Using the command line is actually quite helpful the get in the "git mindset" (and workflow). Give it a try and you won't want to go back to gui tools.
3. Assuming you are on Windows, check out Github Desktop and Tower.
Which pales in comparison to the multi-platform goodness of TortoiseHg since it is an independent creation designed from the ground up for the distributed workflow rather than a reworked TortoiseSVN. I wish someone would do a Git conversion of THG.
I highly recommend you give SmartGit a try. The best way I can describe it is it feels like an IDE for Git/Mercurial. In a similar vein to TortoiseHG. Unfortunately, it's paid software, but one of the few pieces of paid software that I'll ever recommend.
Have they fixed their exrreme performance issues yet? For years the product was completely unusable because simple operations like marking a file would take 10secs while maxing out your CPU. Google for it and you will find many threads on their forum, all with various hacks and solutions that some times work and some times doesn't, the problems seem to be machine dependent so some people get the problems while others dont and they can easily ignore fixing the issues permanently. I haven't bothered to try any updates for the past year since I lost faith in them.
A shame, because otherwise the product looks good and has a good workflow.