Whether you're Alliance or Horde, you have a variety of choices when it comes to your favorite city. Maybe you like Silvermoon because it's quiet and the only people there aside from you are the Alliance who are going after Lor'themar Theron for their black war bears. If you're Alliance, you might prefer Stormwind because there is a mailbox literally right outside the auction house.
As someone who primarily plays Alliance, I prefer Ironforge. I love the dwarves and the lore behind them. The city of Ironforge is housed in a mountain. Whoever had the idea to put a city inside of a mountain deserves a keg of ale. There is only one way in and out of the city, which is good for the defenders, bad for the attackers. It's also impossible to get lost in Ironforge. It's a giant circle with one floor of buildings. Unlike Darnassus, you can easily move between the auction house and the bank.
Of course, Ironforge does have its flaws. While the layout is simple, that is also a major drawback. The architecture of the buildings was awesome in 2004, but in 2010, it's rather bland. Everything looks the same, which can cause some confusion when looking for a certain vendor or trainer.
What goes into choosing your favorite city? Do you prefer Dalaran for the portal room? What does your favorite city lack that others have?