I ran Fedora for a few years on my Dell laptop and I have to say that it didn't just work.
The thing that makes Ubuntu stand out to me is the very large size of it's user base compared to other distributions.
This means that things like edge cases in hardware are much more likely to be addressed, and there will be more chance of other users having the same problem, therefore more chance that you will find a solution.
Ubuntu's competitors were never Debian, but Mandrake Linux and SUSE. Ubuntu shipped out free CDs internationally and encouraged you to take more than you needed to spread the Ubuntu. In the days of 56k modems this was amazing. This was the era when compiling your own kernel was a fairly normal part of desktop Linux tinkering.
Today there are polished distros that just work, Fedora being a great example. Ubuntu wouldn't personally be my choice for desktop or servers for some years now and I haven't used Ubuntu on the desktop since about 2006 and on a server since 2012. Already by 2007 there were nicer out the box experiences such as Linux Mint.
Were it not for Ubuntu (and Mandrake before it), I would probably not have got into Linux until several years later. It was Gentoo, Slackware and Arch that taught me the internals.