Hi, If your using a high-end desktop pc for virtualization use Hyper-V (it can tolerate the use of generic nic's) else if your going to use a branded server I would use "VMware vSphere Hypervisor EXSi" (it has the best disk install footprint and optimized drivers for supported host servers when compared to Hyper-V)... Hope this helps.
Both the virtualization platforms have their own advantages and disadvantages, but choosing one is totally depends on the hosting platform you need. If you want to choose Windows environment, HyperV is more cost effective solution, because you will not have to pay additional charges for Windows OS which are to be paid on VMWare. On the other hand if you want to pick Linux platform, VM is the way to go.
[FONT=Times New Roman, serif]In addition,[/FONT] both platforms are viable and stable however Hyper-V is limited to 4 CPU cores and VMWare is limited to 8.