Whether you get the Fairmont bagels or the St Viateur bagels, you would be a fool to not try a Montreal style bagel while in Montreal. Honestly, I think arguing about which bagel shop is better is a bit silly. They are both good and you should try one of the shops at least...or if you love bagels try both! I've been to both shops a number of times and would say they are both extremely consistent in the quality of bagel they produce. I love their chewy textures and am always happy ordering a Poppyseed, Everything or Sesame seed bagel from either shop.
Just a few things to know...the shop is small (get in and get out); they sell cream cheese ( a couple different brands), smoked salmon, hummus and a couple other items you can top your bagels with; and they price the bagels individuals, by the half dozen and the dozen. Typically the bagels are about $.90 each. Also, you can see the bagels being made while you are ordering.