Depending on when you need to eat, at the airport you can grab Patties and Coco Bread etc;

in Montego Bay on Gloucester Ave you have a whole group of restaurants;
Margaritaville,
THE PELICAN,
THE PORK PIT,
THE NATIVE
and of course KFC

If you can wait 45 minutes to an hour, then Biggas in Green Island is the ticket.

I usually can make it to Biggas and it's well worth the wait.