I wish I were that young 
Each distro has it’s plus points, and it’s down sides. Each distro has it’s own cult following.
There are some that seem to work well for desktop (Ubuntu, Mandriva, SuSe), and there are some that work well for server environment (Slackware, debian).
My experience of redhat enterprise is that you are fine if you only want their approved packages on. Step outside of that and you end up on your own. Debian, and by extension, Ubuntu has a huge range of packages, including bleeding edge, and stable versions of each one.
I personally prefer debian/ubuntu’s package manager (apt) to rpm’s, but thats due to experiences of rpm eating it’s own database in the past.
Most of the distro’s do the job, and which ever one you pick, you’ll get used to. I’d recommend against any of the enterprise versions of a distribution as it’s likely to be limited on the packages it has (in my experience of RHEL), I’d also recommend against Gentoo at this stage. I used it for a year or so, and wouldn’t go back.
One thing to consider is the community support you’ll be getting. Check out the forums of the distributions you are thinking of using, see what is on their wiki, see if you can find information there for all the things you want to do, and see how friendly and knowledgeable the folks on there are. If they know what they are doing, are friendly, and there is information on what you need to do, then that distro will do.
HTH
Endolf