When I want just an all around amazing margherita pizza (without the cheese), Davanti Enoteca is the place to go.
They call their classic pie the DOC. Ordered without cheese, it's amazing. I also add a bit of salt and oregano to top it off. (In a pinch, it's super easy to pick the mozzarella off, unlike most pizzas). The crust is cracker thin, and the sauce is so flavorful and sweet.
It also happens to be located in a very cute neighborhood in Chicago called University Village.