It depends. I do always prefer debian and I always install the minimal installation. It works pretty well with AMD, but newest driver from nVidia doesn't like it so I need to install Xubuntu. Ubuntu is the same but Xubuntu is more lightweight IMO.
thanks again. i'll try to figure out how to create a minimalistic installation for usb myself. i really don't like to have a desktop, just a shell. i'm not a linux pro, but i think it should be possible.