Of the two, I always preferred the flavor of Pepsi. Dr Pepper tastes better, though. My wife drinks D.P. exclusively, so it's always around the house.
Root beer.... has them all beat. It's been my favorite soda for decades. Barq's for the win, though A&W is pretty good!
Red Cream Soda?? I will have to em-barq on a quest to locate this deliciousness!