KVM is a true virtualisation where it has it’s own kernel, independent from the host node. While OpenVZ has no independent kernel and relies on the host for respond for system calls. OpenVZ has it’s own benefit and KVM has his own. If your application needs true dedicated resources and specific kernel module, you have no other option than KVM to go. But if you think your business would grow overtime and you need upgrade fast ASAP or any modification on your VPS as fast as possible, then OpenVZ is your choice. OpenVZ provides more flexibility of use. Though different benchmarks has proved KVM outperform in performance with OpenVZ. OpenVZ containers are usually cheaper.