KDE
Without a doubt.
Reasons I like KDE:-
Kparts - reuse of code for things like HTML render etc
DCop - apps "talking" between themselves
Koffice - not as slow and clunky as OOo imho
Applications - just about everything I need, from KTorrent, to Konversation, that all stitch together nice
Things I HATE about KDE:-
Arts - awful sound system that desperatly needs replacing with alsa once and for al
Great ideas but seem to do it "too high" - eg DCop, amazing, but why wasn't it done 'lower' so other apps can access it. Sort of being done now with DBus. Same sort of goes for arts and now, to my disgust, their automount solution.
I think its a major misconception about KDE being slower and more 'bloated' than Gnome. Most distros just install the whole KDE package when you install KDE. But something like the split kde builds on Gentoo slim down KDE to just what you want. Very very tidy.