your body will absorb most easily. This means trying to match your body's specific electrolyte composition. Water is closer to your body's electrolyte than soda due to all the crap as you said in the soda, especially Utah water with the high mineral content. But if you really want quick hydration, drink a true electrolyte beverage at lukewarm temperature. I assume temperature plays a big factor as well--try drinking lukewarm water vs cold water and feel the difference.