I'm a Mac user since 2007 and I'm totally enjoy it When I work on Windows, it's a pain (spent the last year on Windows 2000, I thought I will die...).
I like most all of them I like almost every one of them but I am a programmer and when it comes to a programming platform Linux is the king. Nothing like having a half a dozen compilers at your fingertips and 100% full control of every single piece of the os and software running on it including the kernel. OSX is a close second since it has a nix core but the os and software comes without source so it is not as open as Linux
Apple is for indy wannabee's who wear converse, tight jeans and single strapped back packs... That's right buck the system apple guys!! Real men use Vista!!!!! (kidding about the vista part)