I am on #gentoo because it compiles for my CPU (-march=native and other flags - not generic x64, but I did not measure the performance numbers), and another point - USE flags and the ability to apply source based patches. For example in Firefox in about:firefoxview in Open tabs we have only 7 elements and no preferences to increase that number, so I found it in the source code and produced a simple patch for my system - and on every update the Portage package manager will try to apply that patch.
