Ive always like the 4 cheese Flat Bread at Mama Melrose. Just yesterday DS 7, told me Mama Melrose has the best pizza.
We also had one with Pepperoni and it was long thick strips of pepperoni...very yummy too!
I agree that good pizza is hard to find at Disney! I also agree that Wolfgang Puck's probably has the best. I recently tried Pizza Planet at MGM too and was pleasantly surprised!