I have been using Centos 6 for primary when doing web related items, but would prefer something more user friendly with wider support. It seems to boil down to these choices right now: Centos, Ubuntu, or Mint. What have you been using?
Out of curiosity, why CentOS? The software in the repositories is antiquated. If you want RPM, just go for Fedora.
All of our production servers run centos, and it makes it easier to just run the same system and use nx/nomachine for compat reasons. I have not had the chance to play with fedora yet though.