room temperature water.
if i'm on N2slin before my workout I will drink a mix of whey, creatine, alcar, and n2carb to help bump my blood sugar and shuttle in nutrients during that window... but damn it makes me heavy during the workout so that isn't often. if you want to feel light and not burpy can't go wrong with just aqua
i would never recommend anything except water for sure be drank during cardio. and unless you did an extensive amount of cardio always use water to re-hydrate, you don't need sports drink or any of that scam bs otherwise.