I was Horde for a lloonngg time. I always preferred the Alliance's races, lore and settlements though, so I moved over a few months ago. Never looked back. I mean, compare Ironforge to old Orgrimmar for coziness.
Alliance capitals actually fit what I, personally, think of a capital - a safe, relaxing place. Spiky orgrimmar doesn't feel like that at all. Though, I'm biased, and I'm sure a Hordie could argue with my point with Silvermoon City. The Horde cities have their charm, like Thunder Bluff with it's amazing views and the feeling of being high up, but I just prefer the gold and blue.
We also have gnomes and two practically immortal races. You jelly? \o/