I tried Slackware, Redhat/Fedora, Gentoo, Knoppix, and Mandrake
Redhat/Fedora and is much easier to use. But u have headache on dependencies and rpm headaches.
To use Slackware and Gentoo is reduced headache.
To use Gentoo is so ez to intall all the program using "emerge" command dont need to bother about the rest. But a bit time consuming to install. But trust me, u will learn a lot of things about installing things from scratch.
For Slackware, it's quite a simple and fast Linux from what i used.