We do seem to have quite a prolific little band of them on here don't we. They've come on a bit since the "you're a fag using a fag computer, all Mac users are retards, etc" days, but I still haven't seen any present a coherent argument as to why I shouldn't use my Mac.
Those arguments don't actually exist, on either side of the argument. For someone who's happy with their platform of choice, and has gotten good-to-great results from their choice, no argument is going to persuade them that they're wrong. That's why the sensible people here point out that OS X, Windows, and Linux all have their strengths and weaknesses, and that people should just use what works best for them.