Most of my GUI usage is "Maximized Xterm window or tiled Xterm windows" these days, so take the following with a grain of salt.
I'm a GNOME man myself, mostly because it's what I'm used to. Ubuntu is my favorite Linux distro, and I've grown quite used to the GNOME way of doing things. Plus, most of my favorite applications are either GTK+ apps (Rhythmbox, Gedit), independent of a major toolkit (Firefox (XUL), Xterm), or aren't even graphical (Mutt, Vim).
I'm spending more and more time in the console, especially on my desktop, these days. Zsh + Screen + my favorite text-mode apps = my new favorite desktop. I think it's because I'm starting to grow disillusioned with GUIs period, but that's another discussion for another time....