A dissenting voice, but I think some of the best Canadian music ever hasn't been made by bands, but individual composers - ie: Richie Hawtin (aka Plastikman) - one of the defining pioneers of the mislabeled "detroit techno" [should be windsor techno, but y'know how those Americans like to hog the glory] (see
Hawtin's Label, Plus8 Records]), or, say, Oscar Peterson, Joni Mitchell, or Neil Young.
But if I had to pick a "band" (how mainstream of me), I'ld go with The Hip or DOA, assuming we're using the same criteria as CBC's "Greatest Canadian" contest..
Devin
Edit: I'm surprised no one mentioned Jeff Healey.. that blind boy plays a mean guitar.