I don't really have a "favorite". Ubuntu is working okay for now, but I've been eyeing Fedora, Debian, and even the BSDs since I'm not convinced that a "desktop" OS is really the thing for me (a former Slackware, Debian, and Gentoo user).
-YaST, makes deploying really simple and configuring tasks that are traditionally done by editing configs
-Build service, it's nice to be able to build your own rpms for various distro's with a click of a mouse or simply download someone elses packages with a click from the mind boggling amount of packages.
-overall look, they go though great pains giving the disto a consistant look
-easily remixed, with it's ability to create your own distro with the built in producf creator you can build an opensuse based distro as you see fit
-hardware detection, got a fakeraid? no problem installing to it with opensuse
Cross-Compiled Linux From Scratch (http://cross-lfs.org/view/svn/x86_64-64/). It's a lot of work, but there's too many quirks in regular distros that annoy me. Every time I try a distro for a few months, I end up going back to *LFS.
Here are some old articles that offer help on installing GENTOO.
All you really need to do to install Gentoo is follow Gentoo's own installation instructions. It's only really difficult if you try to play it by ear and screw up; otherwise it's just a bit of work and waiting for stuff to compile. I have my reasons for not using it, but installation difficulty is not one of them.
Using Fedora 8 since last month. I tried to install F9 preview, but ended up in using the older one as ATI cards are just to much unsupported in F9, yet, even if 8.05 will bring us 2.6.25 support there's still dri 2 and Xorg 1.5 left ;-)
I used Gentoo before but it was too much broken as I always tried out svn versions of everything. And as I was a bit tired of waiting 6 hours for my system update to finish, I switched to a binary distro.