Any time someone talks about the Horde's "deeper story", and how they're the "underdog", I have to laugh. How about the fact that I can point to no point in lore where the horde ever lost for any reason other than dissension in their own ranks? How about the fact that the horde's attitude seems to simply be "join us or die"? How about the fact that the Horde has twice almost destroyed humanity? How about the fact that they refuse to apologize for it? How about the fact that they blame everyone but themselves for their problems? Seriously, all but the Tauren are a bunch of whiny, violent, selfish, killers. Mind you, this is all lore here, what people are in game is another matter (though I find what people I know who rolled Horde tend to be more competitive). In any case, I needed to unload that, the horde is not "misunderstood", they're violent, selfish, and by and large, live to kill.
Also, to all the "kids play heroes, adults play villains" crowd. I find children enjoy antagonizing, because they're built to test limits, that includes yours. Adults tend to want to defend the status quo, sometimes to a fault. Now, I realize people have been attempting to turn the definition of maturity on it's head, but really here.
I play alliance because I like being the guy who would give his life without hesitation to save a complete stranger, the heroic champion of freedom and good, who is not perfect, and the fight against that imperfection is what drives him forward. Not some violent savage who only wants to prove to anyone who will listen that he's stronger than anyone. I mean, hey, you want to play that, that's fine, but don't stand around and pretend you're smarter or more mature because you play a green viking.