That's a big claim. How can I say such a thing? Aren't all Linux distros essentially built on the same foundation? Well, yes, they are. But then again, all cars run on four wheels. What sets Ubuntu apart isn't the fact that it's Linux or even that it's Debian-based, it's the people behind the effort. Ubuntu's core team, Canonical, is doing something no other Linux distro has been able to do. It's giving guidance on and meeting the expectations of the average user. And it's doing it at a rate that's significantly outpacing all of its competitors.
Ubuntu has been the #1 distribution on DistroWatch since 2005 with its closest competitor being Fedora (which it consistently leads by a 30 to 50 percent margin). To find out more about why it's been able to hold this position and gain ground from both the Windows and Mac markets, read this article: Ubuntu, the Ultimate Linux Distribution. And a further clarification here.
With Lucid Lynx just 6 days away, the soon-to-be 20M users worldwide have again turned to Canonical for direction on the next big thing. And they haven't been disappointed. Read more about the recently announced 10.10,