Northern Flickers have my vote.
All of these birds have a wide range and are common in a lot of cities. But there's a special relationship between Flickers and Calgary: they're one of the few cities where they're here year-round (though far less common over winter), and the ranges of the red- and yellow-shafted variants overlap, so we get both variants as well as occasionally hybrids - birds with colour-markings of both types.
It's tough to photograph these hybrids, because the red moustache is easiest to see when it's resting, and the yellow tail-shafts are easiest to see when it's in flight, but I had this visitor to my backyard last fall, who gave a great display of both colour-markings:
https://i.imgur.com/GuH58O7.mp4