Yeah if there is power, no contest. Especially in the southern USA where they sell guns and ammo. You could honestly last years there alone.

Definitely a mega grocery store. Just have to secure all those entry points and loading docks, but it would last you at the minimum a couple of months. Most stocked canned food are 2-3 years out from expiring, so if you have enough of them in the store, you can last that long assuming the building is secure the entire time.