Are they making Parallels Hypervisor open source? It's similar to KVM/Xen and comes with extra tools such as prlctl, making it easier to control than KVM/Xen.
Here is what prlctl offers, looking similar to vzctl from VZ right?
Parallels Cloud Server is based on Virtuozzo, which is pretty much OpenVZ with some extra functionalities.
I have used PCS before, nothing surprising other than some cloud storage features.
BuyVM - 2 Everything is just so good there ;)
HostUS - 2 Good performance
Crissic - 1 had a few network / support issues
I was going to vote for Vultr but they were reluctant on disclosing some information about their networks / hardware.