I like Xfwm since it's the most customisable and the easiest to make new themes for. It's also very lightweight and slots in neatly alongside other desktop-environment software.
Although don't particularly like its very business-like and old-school feel, vtwm does offer a few interesting ideas, particularly in its twist on the "virtual desktops" concept common amongst Linux desktop environments.
madanra wrote:
KDE. I switched from Windows 7 to Kubuntu a few months ago, and I chose KDE as it had most of the things I love about the Windows 7 desktop environment. Hopefully sometime I'll get round to compiling KDE myself, and I'll try and make it even better (for my purposes) than Win7
Yes, I have always thought KDE is the "good-looker" for people switching from Windows 7 and who like all the fancy eye-candy (Compiz is also good for us non-Kubuntu users).