What benefit and services do you get?
You get commercial support and help via several support channels, and guaranteed access to the Proxmox VE repositories for updates and bug fixes.
Every Open Source project needs to be financed by a strong...
You can migrate VMs from ESXi even without vCenter Server.
There are several methods, but I think it would be best to first try the “Automatic Import of Full VM” method.
https://pve.proxmox.com/wiki/Migrate_to_Proxmox_VE...