Best rum for a Rum & Coke: Silver rum AKA white rum is the most common and has a lighter taste. Dark rum and spiced rum will bring the most flavor.Best cola: Coke and Pepsi are the most common but feel free to use any type of cola. Variations:
Make it low-calorie: If you like diet soda, of course you can use that here! I know a lot of people who like theirs with Diet Pepsi, Diet Coke, Coke Zero or Zevia.
Make it non-alcoholic: Try a non-alcoholic rum such as Ritual rum alternative, which is my favorite.
Try a flavored cola: Cherry Coke and Vanilla Coke would also provide some additional flavor. Add your own flavoring with simple syrup if desired.