I love Chicago style (Giordano's in particular). Detroit style is pretty awesome, and different enough from the others that I wouldn't want to give it up.
I've never had the New Have/coal-fired pizza.
That being said, the question for me is 4 vs 6. They are similar, but a well-done #6 is the sex. #4 on the other hand is the easiest to have as a weekly staple. I went #6... but man.