In my personal experience Mac are the closes platforms to this stability; it's probably because the HW and the SW are designed together. Using the same software on other HW would be a terrible experience that would break the only real benefits of the Macs. I have used linux for many (many, really many) years, with many different distributions; I love it; it's my first choice for servers. But not as a developer, because it never gave me the feeling that I can trust it whatever it happens.
What I really need is a computer that can be updated without worries (I'm currently writing on a mid 2009 MBP 13" which got updated multiple times without one single formatting), great screen, fantastic keyboard and wonderful touchpad, because these are the things I touch and see everyday. I wouldn't trade Mac's touchpad for more RAM, neither the great keyboard for longer battery.
Of course these are my key points, while others might have different needs.