What people have said are good indications of why we all like macs, but I have one thing to add, i think our "persecution" by arrogant and obnoxious and sometimes just mis-informed PC users helps this. When you are constantly harrassed about your computer choice, especially when its a choice you make rather than just going with the mainstream you get defensive? Why because its a natural reaction to critcism, especially the kind you get in regards to being a Mac user. When you are called stupid just because you use a different computer without any logical (or at best fallaciously logical) reasoning behind it you want to stand up for yourself. Given that Apple tends to appeal to people who are willing to not just go along with the majority, we are less likely to just give in and change. You tease a dog a little bit it can ignore you, but you constantly tease it and it starts to fight back, then you start blamming the dog for being agressive. I think the same is true about PC users and Mac users. Alot of times you are harrassed because you use a Mac, so you get sick of it and start fighting back, then they accuse you of being a zealot (another attack). Just about anytime I am harrassed now I ask them why its so dumb to use a Mac, then when they start saying the usual things (Macs are more expensive, no software, more people use PC's) I start breaking down their arguments. Either through counter examples, the first two, or taking their argument and replacing it with a similar situation (Just because a majority of people in the world do something one way does that make it better/right). Soon they either realize that they have no good reason, or they devolve into, "well Macs are just dumb" at which point you tell them to go away.
. But, it seems to be stuck because it goes away sometimes 
