I learned Windows years ago, picked up some Apple, and came into Linux/Unixa few years ago. I think that at the heart of the matter, is that Linux allows you more choices over the closed platforms. I think all 3 OS's will do most of what you want, it is just that there way of going about it are different. I think that most people are one or the other because that is what they know. I think Linux is a bit different because a lot of people, like myself, become converts after being told for so many years that there is only 1 way, when in reality, there are many ways.This issue is also on the smart phones as well.

I think Apple does a great job of making things easy, pretty, and idiot proof. Microsoft does allow for a bit customization, and delivers a solid product that has given most of us on this site jobs. Linux has it's pluses and minus.
The big plus is you have as many choices as there are available, or you can create. The biggest minus is there is not one major company that pushes the product to the masses to let them know they do have a choice.

Linux needs a Steve Jobs or Bill Gates. Where is our open source savior?