System Virtualization has become a fundamental IT tool, whether it is type -2/hosted virtualization, mostly exploited by end -users in their personal computers, or type -1/bare metal, well established in IT departments and thoroughly used in modern datacenters as the very foundation of clou d computing. Though bare metal virtualization is meant to be deployed on server -grade hardware (for performance, stability and reliability reasons), properly configured desktop -class systems or workstations are often used as virtualization servers, due to their attractive performance/cost ratio. This paper presents the results of a study conducted on commodity virtualization servers , aiming to assess the performance of a representative set of the type -1 platforms mostly in use today: VMware ESXi, Citrix Xen Server, Microsoft Hyper -V, oVirt and Proxmox. Hypervisor performance is indirectly measured through synthetic benchmark s performed on Windows 10 LTSB and Linux Ubuntu Server 16.04 guests: PassMark for Windows, UnixBench for Linux, and the cross -platform Flexible I/O Tester and iPerf 3 benchmarks. The evaluation results may be used to guide the choice of the best type-1 platform (performance-wise), depending on the predominant guest OS, the performance patterns (CPU- bound, IO-bound, or balanced) of that OS, its storage type (local/remote) and the required network-level performance.