hm, if you want to know Linux I would go with either slackware or Debian.
if you want something that is easy and "works" more or less out of box without effort ubuntu or fedora is what you want.

trouble is that the more "automated" the install and system administration is the more little anoyances pop up, most persons that have used linux for a while tend to choose slightly less automated approach, it is more stable and less prone to suicide.
the packagehandling in Debian is hard to match and the stability is great, Slackware is as stable and somewhat more "standard" EDIT the goal for Slackware is to make the most unixlike (whatever that is) and standard linux /EDIT no fancy patches, nothing flashy, but is rock solid. i would be hard pressed to say which is "better" of the two.
Fedora and Ubuntu are ok but you will only learn THEIR admin tools, not how LINUX work... someone that knows linux (read Slackware and/or Debian) can admin them all but someone that knows redhat/fedora/ubuntu is handicapped if outside his/her distro.