How important is it that the machine also host local graphical sessions? Asking because if I recall correctly, Promox doesn't offer a GUI by default. If you're going to use the machine for anything else, I feel like one would end up installing and configuring more things, in order to also have a graphical environment in Proxmox, than they would to install the preq's for libvirt/KVM under Debian with a graphical install (et al.). Of course, there isn't a snappy web-GUI if you go the libvirt/KVM route (by default), but virsh CLI and Virtual Machine Manager GUI, offer similar functionality.