I have been using Gnome 2 for a number of years, but recently decided to test a bunch of different wms: Gnome 3, Unity, awesome, xmonad, LXDE, and KDE. I gave each at least 2 weeks of use to get over the "change" hump.

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.