I have been a big fan and user of vmware ESXi for years, I started playing with it since circa 2008. The bare metal hypervisor and its easy to use GUI on Windows makes virtualization management extremely easy.
However in the past couple of years the free version of esxi has moved to HTML5 web management, and in the latest ESXi version the Windows client (vSphere client) requires you to pay for a license a run a central vcenter server/vm in order to manage via GUI (non-web).