We also evaluated XCP-NG.

Esxi 

xenserver

We evaluated VMware ESXi and oVirt from Red Hat before choosing Proxmox VE.

Several, From Red Hat to Ubuntu, and everything I can find with a Google search, I spent 6 months with these research and tests!

The Facebook contract came well after this tests .

As a part of my company's evaluation process, we tested VMware.

I made a comparison with Hyper-V and Huawei. I bought Proxmox because it's cheaper and more resilient to our power environment. We have very unstable power in the country, so Hyper-V and sudden breaches in power were problematic.

I just went directly to this product. I'm aware of other possibilities, KVM and others, however, I decided on Proxmox as it had a good following and good documentation.

Tried Xen, but was not comfortable.

We did not evaluate other options. We tried out Proxmox VE two years ago and have been using it since. 

We tried VMware and decided to go with Proxmox VE. The cost was the key factor.

I evaluated several products including Docker, HyperV, VirtualBox, and KVM.

We are looking for another Hypervisor similar to VMware.

I've worked with VMware, vSphere, vCenter, and vRealize Operations Manager. VSphere works perfectly. The enterprise version is very complete, and you get almost everything you need in data center.

We also looked at VMware.

Citrix Xen-Server and XCP-NG