Linux user since 1999. Linux became my primary OS in 2001. Used SuSE before switching to Ubuntu in 2006, have dabbled with Debian and Gentoo.
I use Ubuntu on my MacBook3,1, but I try each new Kubuntu-release on it. One day, if Kubuntu works satisfactorily on the MacBook, I might switch. The MacBook ran OSX for two months. I wanted to give it a fair chance, so I refrained from installing Ubuntu on it. Dualboot lasted about a month and then I wiped OSX completely. I use my MacBook intensively.
My desktop runs Kubuntu.