Chicago might not be among the top 10 worldwide, but there are others that would easily put it in the top 5 in North America. On my list it would rank 3rd behind NYC & Vancouver just ahead of Seattle & San Fran. And are you implying Chicago has nothing on Toronto? I'm a huge fan of Toronto and I'll defend it anytime anywhere but Toronto has nothing on Chicago when it comes to the downtown core. Where Toronto puts Chicago to shame is outside the core.
On my list, SF, NYC, Washington, Seattle and Boston are ahead of Chicago. LA is a push. Heck, I had more fun in Las Vegas. I've done Michigan Avenue. I've done the river tour. I've walked around and looked up at the skyscrapers. I've checked out some art galleries, the blues clubs. I haven't done the museums or aquarium, and I spent no time at Millenium Park.
Unlike San Francisco or Manhattan or DC or Boston, my experience in Chicago has been that it's a lot like Toronto, but minus the fun parts. Maybe it's just that I was there on business, but the place left me cold. And, despite enjoying this forum, I'm not really a building geek, so going on a river architectural tour to see a Mies (like TD), an Art Deco exchange (ditto), etc. was a bit of a yawn, frankly. Beer was cold and free, though.
I'll take a walk from Georgetown up to the National Cathedral and Cleveland Park, or a stroll through Chelsea/Soho, or climbing the hills of SF, rather than walking down Michigan. It was opulent, but I couldn't care less about shopping.
And, yes, maybe I'm biased towards Toronto, but I'll take my rollerblade down the Beach and back versus the Lake Shore in Chicago.
The Tribune building is pretty awesome, though.
BTW -- I didn't say NA -- I said US. You'd have to add Montreal, Vancouver, and Toronto ahead of Chicago in my books, which almost pushes it out of my top ten. I'd need to see Miami, San Antonio, maybe Philly again... but Chi-town I find boring.