TortoiseHg's search bar was amazing at deciding whether you were searching for commit message, author, or what. You'd just type "bugfix pickme" and you'd get back only the commits you needed. Check out master, right-click the batch, graft. I have five different ways to search my Git repo and all of them combined aren't as good as TortoiseHg's search bar with revsets.
Guitar ( https://soramimi.github.io/Guitar/ ) is the closest thing i've found to TortoiseHg for git, really promising but not yet fully baked - with a little help that could be a real TortoiseHg successor.
Everything other git GUI i've tried has some problems (git gui + gitk is reliable and featureful, but no grafting & has that Tk UI; git-cola is crashy and the DAG view isn't properly integrated; qgit and gitg can't push to remotes; sourcetree and gitkraken are nonfree; gitextensions and tortoisegit don't run on Linux).
One feature of git gui & gitk that TortoiseHg badly misses, though, is the option to stage lines for commit instead of just hunks.