There are multiple factors that must be considered when you choose which hypervisor to use. The majority of these criteria have security issues, and as you'll see, there is no universal answer that will fit any environment, but each single company will have to find the best tool for its needs. Also, all these hypervisors have an amazing speed of evolution, so hypervisors that are not ready for production now could be ready for production in a few months.
I believe that a very important part of the hypervisor choice has to be based on your staff expertise. There are cases where it makes sense to deploy a hypervisor where none of your staff has any kind of expertise, and this could also be your situation. The downside of this is that your staff will need to study the hypervisor well before it can go into a production environment.
I would say that this could be considered the economical part of the decision; in fact, it affects mainly that part...