Ranked in these QuestionsQuestion Ranking
Pro Easy to use
Mercurial is designed to make performing operations (such as commits, clones etc.) fast.
Doesn't require access to a central repository, because each checkout is a full repository by itself.
Pro Free and open source
Mercurial is open source and free to use.
Pro Good documentation
Pro Native Windows support
Native Windows support. No trace of cygwin or other dirty hacks typically found in competitors.
Pro Fully python based
Pro Same features Git provides, but much easier to use and to understand.
The command-line interface is more intuitive, requiring much less memorization and exotic options/piping to achieve the same thing you would in git.