Although I agree that Xen is a "no. Just no." for a beginner, you seem to have an attitude against it in a corporate/commercial world? Right from their website, "The Xen Hypervisor has a user base in the millions, that include cloud providers such as Amazon Web Services, Rackspace Hosting, Linode".
I use ESXi as well on an almost daily basis, but you seem to have drank the VMWare kool-aid. That or you are SUPER vendor locked in and so you've given up.