.Net Developers: SVN or HG?

Just a quick question for the .Net developers out there, both Windows and Mono.

Given a choice of Subversion or Mercurial, what would be your preferred source control service and why?  Which helps you work the best?  Which has the  least impact on your workflow?

Sorry guys, I know that some of you may use others SCM's, but I am just interested in these two?