In-depth customization capability. Great community. The new JSON API greatly simplifies custom programming. VERY fast response to questions and issues raised online. Coldfusion (which is not dead) remains astoundingly powerful. It isn't wordpress or (shudder) drupal.
I wish more people had heard about it. Clients who trust me will go with it, but sometimes co-workers and technical partners are deeply suspicious.
Mura is open source technology, created and shared by Blue River. When I started out with Mura years ago, we hired them for some template creation. I feel guilty that I have not had the resources to hire them since then, but that is the beauty of Mura --- we simply could do it ourselves.