Mageia and PCLinuxOS are both KDE based, and pretty well done too.
As for me, I use Fedora (with KDE) myself. I like the somewhat bleeding edge packages (but not Arch-level bleeding edge). yum keeps your system up-to-date. SELinux out of the box is nice, although some people think it's a pain in the ass. Once you configure it it's pretty much trouble-free and provides much better security.
I've got a little script that installs the various extras that that make the user experience much nicer. RPM fusion repo for codecs and nVidia driver, infinality for fonts, also Adobe flash and Google chrome.
Sort distribution in kde or gnome groups is silly when they have both desktops