I don't see a difference, but if the two are before me, I'll pick coke since it's what I drank when I was a kid.
Incidentally, it always amuses me when I ask for a coke at a restaurant and the waiter/waitress says "Is Pepsi okay?" because I work at a restaurant and it doesn't matter whether you ask for coke or pepsi, because you're getting a nice chilled glass of Go-2 Cola.