The Mac offers me access to most of the programs and/or tools that I need, and most importantly is *nix under the hood (unlike Windows). I can sit down and go immediately to the task or job I need to work on, without the various idiosyncrasies I’ve experienced in other *nix desktop environments.
The Mac was, for me at least, the very first environment where I did not have to worry about the OS or system. I could just sit down and work. Of course, controlling hardware and software makes that easier for Apple than just about anything else. Still, it’s a powerful feature that doesn’t appear on any box.