I'm also in southern Ontario and planning a deck build. Was thinking blocks, but will probably do footings.

Instead of an auger, go to home depot and rent the little skid steer thing with an auger on it. They're fairly cheap and you get the pleasure of a machine doing all the hard work for you. Bonus points for it because they usually send it on a trailer with a little bucket too so you can easily deal with the dirt from the hole.