Never seriously used Linux desktop but before several versions of RH, packages were so much older than Ubuntu, it was pretty impractical to use CentOS but people who don't know a thing about servers always chose CentOS because when they Google around, newbie blogs tend to use CentOS for no reason other than RedHat probably was more recognized as a vendor name.

Ubuntu was always easier on the server with root user disabled by default and unattended-upgrades did its job without a hassle with newer packages. (It meant quite different if it was PHP 5 or 7.)