Not a choice but Diet Dr Thunder. It tastes more like real Dr Pepper than Diet Dr Pepper does, and it isn't my all time favorite, but I don't really like the taste of Coke or Pepsi.
Dr Thunder and Diet Dr Thunder are also my call signs on several multi-player online video games I play.
I really don't drink soda any more. Mainly two cups of coffee (black, no cream ,no sugar) in the morning, unsweetened ice tea for lunch, and water anytime else.