So Papa Del's is an institution, yada yada. And it really probably is the best pizza in town---if you know you're coming for a heavy, Chicago style pizza experience. The thick crust is classic Chicago style and is excellent, while the thin crust isn't really that thin but is also quite good. I usually go with their thin crust, knowing it isn't like a New York Style or anything but is instead a less bready version of their excellent deep dish offering. Their sausage topping, in particular, is always worth getting.
That said, I'm not sure I recommend eating in. They are often crowded, their service can be *very* slow. Get takeout instead. Also, their parking lot looks like a giant bomb went off in it. Watch your car!