My favorite trifecta of pizza toppings lately has been grilled eggplant, grilled shrimp, and ricotta (NY or New Haven-style). As for Chicago-style, I had a nice jalapeno pie over at Gullivers on Howard Rd. Indeed, caramelized onions, portobello mushrooms, and (at Limoncello in Cancun) langostinos are quality too, IMO.

Have no grievances with pineapple on pizza - al pastor pie, anyone? - but I strongly oppose mayonnaise. Living in East Asia ruined that condiment for me.