I think the sizes are in reality pretty close and figuring out which is bigger seems very nuanced depending on where you draw the lines. That being said I'll go along with you and say Chicago is probably bigger for the most part right now. Chicago definitely feels like a bigger city when you're downtown anyways.
The numbers you're using for comparison though? C'mon, who's being prideful?
http://www.canadianbusiness.com/blogs-and-comment/so-is-toro...
There are simply more people in the Chicago area. By a decent margin. There's nothing wrong with that. I think this is a thing for Torontonians because of the perpetual inferiority complex we Canadians [2] have with respect to the U.S. :)
[1] https://en.wikipedia.org/wiki/Golden_Horseshoe
[2] I am from Toronto, so it's weird to accuse me of being prideful? I'm guessing you think I'm somehow "defending" Chicago? My point is that having more city in your city is nothing to be proud (or ashamed) about.
Ugh, this is a pet peeve of mine. The city limits are drawn in such a way that Toronto _technically_ edges out Chicago. Torontonians seem to feel this is a meaningful point of pride.
Get real. The metro Toronto area is 7 million people. The metro Chicago area is nearly 10 million.