It's time to update my view of Ubuntu with my most recent set of feelings. Well, with why I feel my most recent set of feelings, which is that Ubuntu LTS is significantly inferior to Red Hat Enterprise Linux.
Ubuntu's LTS releases (Ubuntu 6.06 and Ubuntu 8.04) promise five years of support (hence the 'Long Term Support' label). This support is why we're able to consider them, since we need more than 18 months of support that you get with regular Ubuntu releases; we're simply not in a position to update our servers that frequently.
(There are two reasons. First, moving operating systems in a production environment requires a fairly large amount of careful testing (and a certain amount of dealing with changes). Second, we run login servers and our users do not want to have to do migration work that frequently either; they have better things to do with their time, like complete their PhDs or do research.)
More Here