Pizza is an incredibly subjective thing, therefore I'm going to go ahead and throw out my controversial views. Personally, I feel that Great Plains pizza is barely pizza at all. It's more of a caserole in a bread bowl. Chicago style deep dish pizza crosses the line entirely and cannot be considered pizza. Instead, it is round shaped lasagna. Both are fine if that's what you're after, but when you want pizza you don't want a caserole or a lasagna.
I'm a huge fan of New York style pizza -- large floppy slices with thin crust.