I'm commenting even though I'm not American or Canadian (I'm from Europe actually

), and I'd say the presence of Moscow is almost unfair to the other cities. It's the best one imo, as none of the other cities comes close in terms of height and I like the designs too (I could see myself picking a shorter skyline if I wasn't a big fan of these designs).
London also has some cool skyscrapers, like The Shard, Bishopsgate, Gherkin, or Leadenhall, and I'm a bit biased torwards Paris/La Defense and Frankfurt as I've seen them in person, but yeah, judging by the pictures, Moscow has got this one in the bag
(I'm focusing solely on the skyscrapers and not really on shorter buildings, otherwise other cities would make me think twice thanks to the presence of some beautiful historical buildings.)