How to evaluate a web service framework

I am trying to evaluate different web service frameworks for API development in .Net. So far the frameworks I've been looking at are:

• ServiceStack
• MVC
• Web API
• NancyFx

I'm trying to find some common talking-points between the frameworks so I know what to look for when picking a framework. The talking points I've got so far are:

• The Framework beliefs and principles
• The Architecture of the framework (Client and Service side)
• The Stack the framework provides you with
• The Ease of development within the stack (plugins etc)
• End-to-end performance benchmarks
• Scalability benchmarks
• Framework documentation
• Framework Support (Cross platform etc)
• Pricing
• Overall Conclusion

Can anyone think of anything else I should think about? By the end of the research I'm hoping to write about each framework in detail and to make comparisons as to which framework to chose for a given purpose. Any help would be greatly appreciated.