I'll probably be called a heathen for this from the East Coasters and Chicagoans but since I'm equating favorite to most frequented, then I'll say California Pizza Kitchen. Why? I just like the different flavors and combinations and how their pizza are "outside the box". Here's my favorites (copied from their site):
Grilled steak, fire-roasted mild chilies, onions, cilantro pesto, Monterey Jack, and Mozzarella cheeses topped with fresh tomato salsa and cilantro. Served with a side of tomatillo salsa.
Grilled Jamaican Jerk spiced chicken breast with our spicy sweet Caribbean sauce, Mozzarella cheese, applewood smoked bacon, mild onions, roasted red & yellow peppers, and scallions.
Sauteed shrimp, mild onions, roasted garlic, Mozzarella cheese, fresh oregano and Italian parsley with a white wine lemon-garlic butter sauce.
Mild Goat cheese with roasted red & yellow peppers, grilled Japanese eggplant, Mozzarella cheese, carmelized onions, Italian parsley and our tomato sauce. Applewood smoked bacon added upon request.
A combination of grilled Italian sausage and sweet Italian sausage with sautéed wild mushrooms, caramelized onions, Fontina, Mozzarella and Parmesan cheeses. Topped with fresh herbs.
A spicy marinara sauce with sweet Italian sausage, spicy Capicola ham, julienne salami, Fontina, Mozzarella and Parmesan cheeses. Topped with fresh oregano and basil.
The classic Italian pizza. Made with imported Italian tomatoes, Mozzarella and fresh Mozzarella cheeses topped with fresh basil and Parmesan cheese.