Boy is this a fun thread. It's hard to say which "modern" boxes are the worst because there are so gosh darned many of them and so many of them look alike.
And I gotta laugh at the idea that Denver's skyline is great. Most of it was developed in the mid-late 70;s and very early 80's...when tarted up boxes and brutal concrete were the rage.
My picks? These painted concrete monstrosities in Chicago. They're an insult to this magnificent skyline:
http://www.emporis.com/building/gran...chicago-il-usa
And then there's this crappy squat box in Cleveland:
http://www.emporis.com/building/nati...eveland-oh-usa