Pimento cheese is a huge part of my Southern family's heritage, including its ubiquitous appearance stuffed into celery sticks on the relish tray at all holidays and other assorted fancy occasions. And, although we've tried it with every commercial mayo made, in our house, the consensus best is Duke's.
Which (I just feel like adding) we all know means absolutely not one blessed thing to other families that also have tried all of the commercially-made mayos and chosen something else, bless their hearts. We just think Duke's is creamier. And ain't life grand?