Pirana CMS Comes with lots of features as mentioned here. but it lakes demo website and admin interface. Greatest thing would be that it already uses MVC Framework 5 and Web Pages 3 and its compatible with web matrix ( open source alternative of Microsoft visual studio). another good thing is its simple to understand for any asp.net MVC developer, since it utilizes code asp.net mvc coding style.
Better CMS One of the best WHYSIWYG User interface. where user can generate and publish content right on website with few clicks. It has nicely written documentation but lacking of free modules and themes to get started with. lake of community support as on APR-2014. But its backed by Devbridge Group and their Professionals.
Orchard CMS Orchad CMS has huge community modules, themes. some of them are free others available at reasonable price.
Umbraco Umbraco is considered as wordpress competitor. and indeed it has huge community support and comes with lots of features, nicely documented, and video help is available.Only disadvantage seems its user interface, which is not as intutive as it should have been. there is nice discussion to go over before choosing umbraco.
kooboo Supports Multiple Sites, And ready for enterprise use. Has forum to discuss ideads and issues. Kooboo has online demo website. but it seems it requires registration before demo.
MrCMS Was launched in 2013 and then after rapid development it has got huge list of features, including Support for Sql Azure, and MVC5. But documentation is not yet complete. I believe year of 2015 is going to be a year to polish MrCMS and release documentation and help as possible. Good luck Mr. CMS.