Linux distributions are operating systems for desktops, servers, laptops, netbooks, mobile phones, and tablets (and some minimal environments). These poll choices are only a few of the many different ones out there. Specifically, they rank among the top ten on DistroWatch (over the last 12 months).
I run Fedora and siduction. Always a problem when you can only vote for one. With Fedora, you can see all the newest technology first, with siduction, we get to see things like the new QT desktop first. I like my bleeding edge distros, I also like how stable the devs make them.