I normally us MSTest as I like the integration with Visual Studio. At work we do a lot of NUnit and it just feels dirty having to run my tests outside of Visual Studio (we don’t have a runner for VS). Well we finally got a VS upgrade and I was able to install the NUnit Test Adapter for Visual Studio 2012 and 2013, http://nunit.org/index.php?p=vsTestAdapter&r=2.6.2.
I just installed it through the Extension Manager with Nuget, easy peasy. Now I can run NUnit tests without having to run the NUnit GUI or command line manually. Tests will appear in the VS Test Explorer so organizing, running and debugging tests is incredibly simplified.