Apple is about ease of use and a friendly environment to the customer.
Yeah sure there are other Mp3 players that are better, but the problem arises from other things, I can't remember exactly what it is but it has to do something with the music companies and the chaotic requirements some songs need for certain players. I think it's DRM but I'm not sure. Where as Apple supplies basically every song out there, for good prices, and every one of those songs is easy to obtain and will always work on your iPod or in iTunes. iTunes is also quickly becoming the number one music store in the world, proving that it works and works well. That's what makes the iPod the best.
Along with ease of use and stability is the fact that all the hardware is predetermined. Yeah sure it doesn't mean you can customize that well but all of there machines are good quality to begin with and don't really need to be upgraded that often (as I said before, new versions of their OS run faster, with more features, and are sometimes smaller on the same system requirements as the previous version). With all the customization you can have with Windows comes issues. You're never guaranteed a certain configuration of hardware will work properly and most people don't have the time, patience or desire to deal with those problems. Apple gives the users an easy to use, user friendly operating system and machine set up. Any issues you may have are dealt with by a great technical support team at every Apple store.
You have to realize that the majority of the world don't care about the details. They want something that will work for their every day needs, do it well and without problems. Macs offer this it's just no one is willing to switch over just yet.
Besides, in the end Mac is going the right way. Computing is becoming portable. With the iPhone and iPod Touch they have started the next level of computing. Why bother with a laptop or home desktop when all your files can be accessed, altered, etc, from your pocket? Window can continue trying to copy the features of everyone else, while the rest of the world moves on.
Oh and in case you mention gaming on an portable, doesn't really matter. Consoles will eventually become the only form of gaming anyways because of the fact you don't really need to install or screw around with hardware, you just put the disk in and play.
Humans crave convenience, therefore it will always win.
This is probably my last post on this as there's almost no point in trying to explain this too any of you.