I have heard much good about Ubuntu and decided to try it. I'm happy. It's basically Debian, but polished-up and updated to modern versions of the Linux kernel and other software.
Getting Ubuntu to work with a RADEON X700 video card was a breeze. It wasn't an out-of-the-box experience though. I had to apt-get install the fglrx driver manually first, X wouldn't even start by default. Also, when upgrading the kernel, I had to reinstall the fglrx driver to generate the up-to-date module.
So it's not perfect, but it works very well if you're used to Debian. The Ubuntu people have clearly put effort into smoothing out the problems that make Debian difficult or strenuous to use. Such problems are usually related to non-free software, which the Debian people obviously don't appreciate much.
Ubuntu also has several package sources in /etc/apt/sources.list that are commented out by default. When you enable them (universe and multiverse), you get access to some very nice precompiled packages such as MythTV and MPlayer.
I've been using Debian Unstable on my home server for a few years now, and I've become more and more dissatisfied with the stability. I need the up-to-date software that comes with Debian Unstable, but I'm fed up with the dependency problems and being threatened by aptitude to delete 90% of my packages every time I upgrade.