Ubuntu is merely decent to me, I don't like the full-sudo adminstration idea, I've never heard a convincing reason for why its existance, and while everybody says "SECURITY" I see more to suggest it's less secure than su w/ root when used correctly. Also, Ubuntu's fringe packages tend to be a bit buggy.
Debian is nice, but it's pretty old software. It's not that bad really, it's just annoying, I like having a recent version of VLC. Meanwhile, Testing/Sid lose the stability that makes Debian great.
I hate the way SuSe makes YaST the "one utility to rule them all." The fact that NVIDIA has a special SuSe guide for installing their graphics driver, and no other distro has/needs a specialized guide says enough.
I like Slackware, I just wish more people built packages for it, especially library packages. I can't put up with it in reality because finding certain libraries is such a pain, makes you wonder how the Debian people and such have them in repo if nobody can find them.
PCLinuxOS is sweet, I just wish they had a more diverse package selection. Including Ndiswrapper drivers is smart.
Zenwalk is like Slackware that can actually be used, Netpkg is a simple and effective package manager, though it has even fewer packages than PCLinuxOS. It's stable, fast, has out of the box multimedia, great wireless support, and is very up to date if you run a netpkg upgrade every so often. And yet, all the Slackware tools are still there if you want to do it the old fashioned way. This is the distro I gave to my mom, and you should see why if you use it.
Despite that glowing review, I'm currently moving to Red Hat type distros, CentOS 5.1 right now but I may go to Fedora 9 when it's released soon here. I want to familiarize myself with it some since I intend to go for the Red Hat Certified Engineer cert in the next year or so. I'll end up taking the Red Hat courses anyway, but I may as well start poking around now.