Chicago is Manhattan for Americans that cannot stand the filth and mobs of Manhattan. A little smaller than Manhattan, but with most of the upsides.
As far as 'real cities' go, very few cities in the world can hold a candle to NYC.
In reality, and as Clem knows, I get a kick out of most American cities. One of the best times I ever had was in a Chicago bar with a horde of screaming Bears fans drinking beer and eating heart attack food.