Ding ding ding. We have a weiner!
This is such a hard list. I'm not at all a brutalist fan, but can appreciate the best examples of this era - basically Robarts, New City Hall (it's a rather warm and inviting brutalism), perhaps U of T Med Sci and a few others, but it left us with disasters, like Ryerson Library/Jorgenson podium, Pri's 77 Elm and Grange Park and 666 Spadina towers (though his stuff in Annex and at Jane/Exbury is worthy). I think Sheraton is a really unfortunate mistake, and has an extremely dead street-level right across from City Hall and on one of our premier streets (also my main complaint with the Opera House, also dead to Queen).
Then there's the lo-po dreck, like the towers on St. Patrick. Or the just bad low rises that Archivist posted. RoCP is just really unfortunate as well, that they turned out poorly, and f**ked up the Bay Street Old City Hall view terminus.