Definately the pepperoni has to be top.
Other hams than pepperoni can be as useful though.
A nice lady from Italy does the same for me when I go to her restaurant and order one of their pies. The crust edges are bubbly like chiabatta, so it's good to order a side of live oil to dip the crusts in. Or better yet, buttery garlic wine sauce.
Man, I'm hungry now.