I've recently grown pretty enamored with Ubuntu 12, and the ease of package management. For me, the growing integration with LXC (which I love for the benefit of "light" VMs / isolation) is becoming buttery smooth.
Support has always been a question, but in 8 years of experience with approximately 50+ servers at multiple locations and clients, I've not once needed to contact RedHat.
Even if I switched to Ubuntu/Debian on the desktop, I'd probably keep CentOS on the servers. While its packages may be old, most things still compile on it.
A long long time ago I took a preference to RedHat/Fedora (well, pre-Fedora) as more software compiled by default on it than on Debian/Ubuntu.
I did once venture over to Ubuntu with the promise of clean upgrades from release to release. In truth, it was no better than Fedora, and I found issues hard to fix.
Red Hat - 991
RedHat - 769
CentOS - 383
RHEL - 350
Ubuntu - 250
Debian - 125
I love Ubuntu on my personal laptop, but RHEL, CentOS, and Fedora are what I've used at work most.