If hypervisor is commodity, why is VMware still on top?

Microsoft and open-source rivals lose it in the labs

The hypervisor is a commodity. VMware's ESXi, Microsoft's Hyper-V and the open-source community's Xen and KVM are all right and proper tools for virtualising workloads. Does that mean we should all stampede away from expensive proprietary hypervisors and dine on the open-source freebies? This being IT, the answer is "it depends"."