KVM vs Hyper-v 2012 Performances

Hi,
right now am using Openvz (under Proxmox) for Linux VMs and VMware ESXi for Windows VM
and I want to move from VMware to other platform
options:
1. KVM
2. MS Hyper-v 2012

Considering I've already work with Proxmox for Openvz and the Differences in performance between KVM and Hyper-v 2012 (if any - I don't know)
What would you recommend me to work?
KVM or Hyper-v 2012?

Best Regards,
Star Network.