A few personal favorites that don't necessarily get much attention. These are obviously a tad Calgary biased... because that's what I'm most familiar with in person.
Canterra Tower by
diamonD.edgE, on Flickr
Canterra Tower in Calgary
Not the biggest anymore... or ever. But considering when it was built, the look as aged very, very gracefully, and it still manages to look really modern. It walks the fine line between visually bland and visually busy, and looks absolutely awesome from any angle.
Calgary night lights by
Surrealplaces, on Flickr
Centrium Place in Calgary
It's pretty small, but I'd argue it's one of the best, most elegant executions of a tower accentuated by LED lighting that I've ever seen.
(From Wikipedia)
The TD tower of Brookfield Place in Toronto
I can see how this tower is a bit polarizing. But, dammit I love it. I think it's one of the most unique and instantly identifiable towers in Toronto (besides the obvious).
Montréal - Tour de La Bourse by
moyogo, on Flickr
Tour de la Bourse in Montreal
I dunno. That picture just screams cyberpunk to me. There are a few similar towers in Calgary (like the Altius Centre) that, for some reason, don't look nearly as cool. They really got this one right.