I guess it depends on the usage. I'd go with windows when it comes for games and simple usage of computers.
Linux for fun tweaking (I didn't try all the distro, so I don't really have a favorite one).
And a small note for Ayman, when you say windows --->$<--- with this sign next to it, and you do not put it for Mac Os... I find it very weird, since all apple do is rub your money, in the end it is their motto: "People will buy anything that we market, even if it costs 500$ we sell at 1000$ people will buy it".
So to be fare, the $ sign must go to windows and mac os smile
I forgot to add that :/ , okay i will add a '$' to Mac O$ to be more fair :D