For me the biggest thing about Ubuntu is that it does not feel like a distribution. It's an OS. They don't just pack others stuff inside one image and call it a day. Ubuntu does things in a way that they feel is the correct way. If there is a suitable OSS package for that, great. If not, then they make it. Fedora, Debian and others just gather what's there and ship it. AFAIK Elementary OS is the only other distro that works kinda like Ubuntu, but it looks like an OSX clone.