In my company I am working as a sysadmin, we using RHEL because it is certified by the Oracle databases we are running. As far I administer RHEL or Centos on my work, I must say that this distro has high quality standards and the best commercial vendor support compared to the other n,n+1,n+2,n+.. flavors of Linux.
Anyway, I am planning to switch some other type of servers on FreeBSD