The best virtualization technology for one person may not be the ideal for another person / company.
There is a bunch of virtualization technology with different costs and functionalities plus some have a kind of phylosophy.
The best thing to do according to me is to write down your needs, your budget and go for a hunt. Find the best solution for you, the one that can be used, the one that will fullfill your requirements and the one you can afford.
Some leads here : Hyper-v, vmware ESX, xen server (the technology we use for our Public Cloud).