Well my preference goes to Ubuntu!
I like the slick and light design (it can be made to look like a mac osX in no time)... Redhat is too conventional and old styled. Plus the rpm installations... BLEH.
Synaptic, the package installer in Ubuntu, is very good and efficient.
Minor tweaking required in my case at first but then it's all good: by far it was the easiest installation I've been through.
Go for it!