I drink more soda than most would think was humanly possible.
Growing up, my mom always had Tab in the house, so that's what I drank. Eventually she switched over to Big K Diet Cola (Kroger's house brand). That's what I prefer now. It's basically generic Diet Coke. And despite what anybody tells you, the generic stuff is not all the same. I can taste a huge difference between Sam's Cola (Walmart brand) and Big K (Kroger brand). I also taste a huge difference between Big K and Diet Coke, but I still like both. I don't care for Diet Pepsi at all though.
After the Diet Cola, my next favorite is Dr. Pepper, followed by Mtn. Dew (or the Big K equivalent).