According to the North American Vexillological Society, Denver has the 3rd best looking flag in the nation. In a 2004 internet survey, the design qualities of the flags of 150 municipalities in the U.S. were rated and Denver’s came in just under Washington D.C. (#1) and Chicago, Illinois (#2).
The top three worst designed flags originate from Rapid City, South Dakota (#148), Huntington, West Virginia (#149), and lastly Pocatello, Idaho (#150). The flag for Pensacola, Florida is horrible but didn’t make the list.
Personally I’m particularly fond of the flags hailing from Oakland, California (#47), Ocean City, Maryland (not listed), New Orleans, Louisiana (#5), and Mesa, Arizona (#146 but they have since created a new flag).