I'm not quite clear why you would want to run virtual machines on a server?
To me, the basic requirement for a server is that it should provide
the services that are required by laptops, phones and other machines.
One reason for running CentOS on servers in my case
is that the CentOS team seem to put reliability and stability
at the top of their priorities,
while when problems arise under Fedora one always hears the response
that Fedora is a "bleeding edge" project.