Some people argued that there is Sun's enterprise support for Solaris and blah-blah-blah. =) Where is the [Open]Solaris now? (Do not even try to tell that it is alive - no activity, no community support, no device driver updates or even patches - the very dead. =)

two hints: There is the CentOS, which have a much cheaper support (free updates + community support). =)

Fedora 12 (even 13) is pretty stable and actively supported system. They got less hype than Ubuntu (they don't have so much money for promotion and advertisement) but it is not just a testing branch of RHEL (look at RHEL6 beta - it is Fedora 12), it is probably the best distro available. (Think about it to become a RHEL with maturation - this is the main advantage over ubuntu which will become only yet another ubuntu. =)