Both Debian and Ubuntu are just great. apt/dpkg is as powerfull as portage (yes, you can even compile your own Debian), choice of packages is unbelievable.
I was using Debian for several years, still using it on servers, but I switched to Kubuntu on desktop. I'm at the stage when you don't really have time to make your favourite mail program running, and on Kubuntu everything just works.
Yes, I know, I'm lazy