Micrososft (Hyper-V, etc)
VMware (ESXi, Workstation, Fusion, etc)
Citrix (XenServer, XenClient, etc)
Plus 99.99...% of all the PCs out there net boot PXE.
In this case I humbly think that "having more features" (that not always work) has been a mantra
for long time recited by iPXE...