Flavored sparkling water from Kroger, Walmart or Dollar general. Zero calories, basically no sodium, and relatively little potassium. I drink a liter bottle every day. About the most kidney-friendly soft drink I can find besides water.
Most flavors actually even taste good.
Nothing with phosphoric acid. Brown colas mostly. All bad.
However root beer is citric acid.
You prob know all the basic though.
Doc told me mt dew was ok. Dentist would disagree. 😃