Another vote for KDE3. I could have just as easily voted for Gnome, but I didn't want to annoy any more people than I already have....

KDE3 works. In my cosmology, "Just Works" is a hell of a lot more important to me than "Brand New" or "Looks Real Sharp". If I get in the mood to experiment, I'll find a spare partition on the basement computer and see if I can get Lenny to work. Pardus--hey, I live here, man! It's for getting stuff done!
The fact that our beloved Pardus development team has designed a KDE interface that is sleek and attractive, and not uglier than a kickboxer's brainscan, is a welcome bonus. If they go with KDE4, I'm sure that it'll be as good a KDE4 as you can get. I'm just not sure what "best possible KDE4" means right now.