You may find some other pies worthy of mention, however, to me after a lifelong pursuit of quality foods in general, I only talk about two. Santarpio's in East Boston, and the original Pizzeria Regina's on Thatcher St. in the North End. Both offer pizza roughly in the Neapolitan style, thin crust, psychotically hot oven to apply just the right amount of char. The toppings run the usual, but I urge you to keep it simple. Sausage is fresh homemade in house in both places, garlic, pepperoni, you get the drift. Both are extremely characterful places to eat, and offer classic and historical Boston experiences. Santarpio's also offers grilled BBQ lamb and steak tips, and sausage. When you're North of the city, try Bianchi's on Revere Beach, the oven has been running for over 50 years, and they also make their own sausage. Takeout only, but you can cross the street to the beach and eat your pie on a bench!