My grandfather always said that Chicago was a city full of hoodlums run by crooks, and that even though you took your life into your hands going there, they still looked down their noses at people from Detroit. He loathed Chicago and anything associated with it. My parents have never gone back to Chicago since George Halas sent a thug named Ed Meadows in to break Bobby Layne's leg in the final game of the 1956 season, costing the Lions a place in the championship game. And Lion fans who objected were taunted, beaten and abused by Chicagoans in the Wrigley Field stands and the surrounding streets. Add to that the various other rivalries, particularly with the evil Blackhawks, and you have a city that a lot of Detroiters have developed a visceral dislike for. It was certainly drummed into my head from an early age to hate the place.
NYC, on the other hand, was a 'real' city, and we went there several times when I was a kid [[I also had some relatives there). Our teams were never in the same division, so there was little rivalry there [[except with the Yankees, but every baseball fan outside of NYC feels that way). NYC was not like Detroit in any way, so there was no real comparison to be made. I lived in NYC for many years, and really loved it there, in part because it felt novel - so different from the city I grew up in.
I was surprised though when I finally went to Chicago that it's actually a pretty nice place.