Montmartre bakery uses the best ingredients and as their bread is baked on site and sold very quickly (there's almost always a lineup) it is always fresh. Croissants use butter, flour is unbleached, and there are no preservatives. You'll get lots of fruit in the massive strudels.
Prices are well below what you would get at premium stores (Loblaws, Longos, Metro, etc).
The selection could be better, however.