I'm a fan of the T&T Supermarket on Mavis. I've been to other but this is the one we prefer.
We will travel for one hour each way to go there and there are a few reasons for this. Fresh everything.
Live lobster, fish and crab. Clams, Oysters and sometimes even live shrimp.
The meat is cheaper there and looks better than most places in the falls, fruits and veggies section is huge with stuff I've never seen before.
But my favorite reason to shop there is the prepared food section. I stock up on spicy chicken, BBQ pork, roasted duck and other goodies each and everytime I go there. Yum