I'm a Ubuntu user. Here are my reasons why:
1) From all of the distros I've seen, the Ubuntu developers take disabled users into consideration more than other distros I've seen. Now that I know how to use the technology available (thanks to a lot of support from the Ubuntu Forums, the Ubuntu Accessibility Team, and the developers of the assistive technology (like the GNOME screen magnifier gnome-mag)), I am no longer a Windows user.
2) Out of all of the distros I've seen, Ubuntu has the most support that I've come across. The community at the Ubuntu Forums is wonderful (I am under the name RKCole there). Thanks to their support (and from the support here, as a matter of fact), I can now do things in Linux that I never would have dreamed fo doing a few years back.
3) I have used Fedora in the past, but I have found that Ubuntu si the most user-friendly and it is not too difficult to use.