Regarding the Musique Plus Building, I prefer the "before" as well... As mentioned, all it needed was for the metal to be painted/cleaned. It went from being a nice example of the International Style to a generic glass box.
Some people also want the same kind of renovation made to the Rogers Building which looks quite a bit worse.. I'm more undecided on this one.
Ugly - Rogers building by
Vanishing Montréal, on Flickr