This is entirely a matter of opinion. Someone who is more familiar with a certain operating system will definitely tell you that's their preferred choice.
I myself have used a lot of Windows (3.1, 95, 98, 2000, XP and Vista) personal computers, and have worked in environments based entirely in Microsoft Windows. Although I can handle it pretty well, my personal choice of computer is Macintosh and I use Mac OS X.
There was a time in which I thought about buying a MS Windows PC mainly to play some Windows/DOS only games. However the urge of having a few hours of fun playing games didn't outweigh the fact about the expense and an addition of yet another system into my home, another computer to keep up with, updating, upgrading, the room it would take (which I do not have) and the worry of it getting viruses, getting infected with spyware, etc. Yet my Macintosh computer can do everything I need, and I don't have to worry about those things, so I soon snapped out of it; specially when I learned to use DOSBOX in my Mac. We've decided we will eventually get an Xbox for gaming and there's no need to worry about spyware or viruses getting in it.