VMWare ESXi
I’ve recently been using VMWare ESXi 5.5 in anger – with real VM’s rather than just testing shell commands. Plus it seems the last couple of versions of VirtualBox can no longer run ESXi as a guest.
Anyway, its soooo Windows-centric vendor-locked its unbelievable. I mean you can’t even load a bunch of ISO’s on a USB stick and put them in the back of the machine, you have to transfer them using the VSphere client over the network.