It depends on what you do with your computer.
1. If you just read web and stalk pretty girls then ubuntu is the way to go.
2.If you want bleeding edge and in other words broken distro to play with choose fedora.
3.If you want develop software choose CentOS or RHEL or debian
4. If you want serve your own blog choose debian, CentOS
5. If you want to hack "cat" or "rm"'s code choose FREEBSD
6. If you want to steal bandwidth from your neighbor's wifi then choose Black track linux
7. If you need a free platform to do heavy duty number crunching choose Scientific Linux( out of the Box R platform is a gem)
8. If you want to hack linux itself choose gentoo.
9. If you wanna brag about your box choose LSF