I've used all of these window organizers before with Gentoox, Kubuntu, and Fedora 9. As far as this goes, my favorite is KDE, pretty much because it looks nice, and it's easy to use. If you vote, please explain why.

I'd use Gentoo or Arch before Ubuntu. Otherwise, Xubuntu for XFCE. The only difference between these Ubuntu "distros" is the window manager they come bundled with on default. You should have just asked what was our favorite window manager as that's essentially what this topic is about, not everyone uses Ubuntu you know. Also, KDE is trash.

They are not distributions, as tehnick rightly said. They are different flavours (different DE or Window Manager) of the same thing.

For the longest time I used KDE but now I use Gnome.
Can't say why , just do.

Whenever I use Ubuntu, SUSE, Fedora, etc I always use Gnome to get the graphical features, but on on Arch and Slackware I always use Xmonad Tiling Window Manager.

So far my favorite is PekWM. Very configurable (and no XML like Openbox!), supports tabbing and lots of other nifty things, and is by far the most theme-able WM I've ever seen. I will likely convert to a tiling WM soon, though.

If I had to go with a DE, it'd be E17 (buggy, but slick and faster than Xfce) or Xfce (lightweight and stable, simple compositing). Maybe KDE, maybe... it's masssive and buggy (IMHO), but I really hope it'll get more stable in 4.4, as I end up enjoying it anyways.

I stick with Gnome, but consider Xfce to be a close second choice. I do not care for KDE at all, but that's just me.

FVWM.

And btw. KDE, XFCE and Gnome still are DEs, not DMs or WMs.

compiz