It's been nearly 10 years since I've used KDE full-time. With the lack of support for Gnome 2 and the clusterfuck that is Gnome 3, I'm tempted to give it another shot.
I hadn't used KDE since Mandrake days in the late 90's, and had a negative impression from the KDE 4.0 issues. But have been pleasantly surprised at its utility and configurability while still looking good on both my 10" laptop and 24" desktop.
I can tell you that it's stable as hell. If it wasn't I was going to be forced to make backup of my PC and install 11.04, but It's running so great that I don't want to waste my time on doing that.
On the other hand, with the release of Kubuntu 11.10 this month, I will, just for the sake of staying up to date with all the packages :) and plus, becaue of KDE 4.7! :)
Which one did you end up preferring?