I like it because it's free, customizable, flexible, stable, secure, etc. I hop around distros a lot, usually end up coming back to the Debian/Ubuntu family. I'm currently giving OpenSUSE a trial, and it's a very clean, polished, professional distro. They make some very odd decisions, though (some software packages are only available on their website with the OpenSUSE Build Service, and not in the normal package manager... that seems to defeat the purpose of having a package manager, but whatever) and of course the software selection in the repositories cannot hold a candle to the all-encompassing glory of the Debian repos. It had an excellent installer, though. Even managed to correctly guess that I wanted to keep Windows there and replace my Debian install, and handled all of the partitioning correctly to achieve that.
I've normally been a GNOME guy. I'm giving KDE4 yet another try along with SUSE. I may have to migrate away once GNOME 3 becomes standard (and Unity is no better), and there are a few nice KDE apps like Kile that I want to use without loading so many extra libraries.
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WAR IS PEACE
FREEDOM IS SLAVERY
IGNORANCE IS STRENGTH