It would be an interesting topic for a separate thread. Putting aside economic realities, which demolished building in Toronto would you most like to see rebuilt?
I don't think the old TTC/Board of Trade building was demolished for (what I still think of as) the EDS building. Even more sadly, I believe it was demolished for surface parking, IIRC.
This pretty much covers most of mine:
I would add to it Union Carbide Building on 123 Eglinton, Shell Oil Tower at the Ex, the Provincial Lunatic Asylum (ex CAMH), Trinity College at Trinity Bellwoods Park, the Normal School, the University Avenue Synagogue.