Ubuntu is a good distro, but I prefer Fedora _specifically_ for its security. Fedora is
generally much faster at repairing vulnerabilities, and Fedora is less likely to be harmed by
a newly-disclosed vulnerability in the first place.
First, for response, just look at your sample. 4/6 times Fedora was faster, often by 2-4
weeks. 1/6 they released the same day. 1/6 Ubuntu was one day faster, and only by a fluke of
Fedora also has lots of protective mechanisms for 0-day vulnerabilities, so it's a lot less
likely that an unknown vulnerability will be as harmful in the first place. SELinux is the
most obvious and pervasive mechanism, but the various exec-protection mechanisms are a big
deal too. I think this is at least as important, even though it gets less press.
There's no need for distro-bashing; they're both good, and there is no magic in what Fedora is
doing. Fedora 9 copies in upstart from Ubuntu, simply because Ubuntu's upstart was better
than what Fedora had. Ubuntu just needs to learn from Fedora in what THEY do right, and copy
the good stuff.