Personally . . .
I find E16 far too fat for my purposes. I've finally started getting used to the tiling window manager life, which opens up a whole new range of minimalist window manager possibilities -- but even before that, I was using a window manager a tiny fraction of the size of a single minor source file for E16. I guess it's all relative.
Amongst the "desktop environments" (including GNOME, KDE, XFCE, GNUstep -- everything that qualifies), though, E17 is not bad. It does some pretty intelligent resource management, so that (unlike GNOME and KDE) it tends to basically "turn off" a lot of it when not in use, keeping resource waste to a bare minimum for what it provides.
