Unless you are in GA the home of Coca-Cola, or in NC the home of Pepsi, there probably isn't much difference in the choice you make as far as the customers are concerned.
However, the dark cola products will be your best seller, the other products that both companies carry will make up the bulk of your sales. I believe that is what makes a difference in the products. I believe that Pepsi having Mt. Dew, Dr. Pepper (in this area), A&W Rootbeer makes it a better selection. However, Coca-Cola having 7-Up is a plus.
"This business isn't about what the customer sees...It's about what the customer believes!"