Great question Ariel...I do have guidelines, which could be turned into a matrix I believe! What my teams use today are guidelines for evaluating SLA's of cloud providers, guidelines for calculating TCO of cloud providers, and guidelines for cloud contract negotiations. I have blogged about each of these topics previously, and below are the links to each of the blogs. I know this isn't exactly what you were looking for, but hopefully it helps. My teams certainly have utilized it well for us.
- Contracting with cloud provider part 1: http://www.ciotalkradio.com/Blog/so-you-need-to-negotiate-a-contract-with-a-cloud-provider.html
- Contracting with a cloud provider part 2: http://www.ciotalkradio.com/Blog/part-2-so-you-need-to-negotiate-a-contract-with-a-cloud-provider.html
- Cloud service level agreements: http://www.ciotalkradio.com/Blog/part-3-cloud-computing-service-level-agreements-sla.html
- TCO of cloud computing: http://www.ciotalkradio.com/Blog/tco-of-cloud-computing.html
I think that would heavily depend on the use case. I've been both on the buying end in marketing procurement and now work in solution design. Uptime goals, scalability, security needs and support are some of the main factors that play into solution selection.
Disclosure: I work for Rackspace
Between AWS and Azure, what is your platform of choice? What makes it your preferred platform?