My personal beverage choice is diet Pepsi.  I probably drank Coke when I was a kid and remember actually taking the Pepsi Challenge.  I actually chose Pepsi.  And then about 23 years ago or so (somewhere around 1990), I started drinking Diet Rite (the diet version of RC Cola) and liked it.  Then I discovered diet Pepsi and never looked back.  It's DP for me.  Diet Coke from a fountain is an acceptable alternative, but I really don't care for diet Coke in aluminum cans.  I just don't like regular (non-diet) colas of any kind anymore.  Regular root beer, orange soda, things like that are okay, but not cola.