I dunno I'm skeptical about different flavored drinks in the bong having a noticeable effect on the smoke. I've heard that even though thc is only soluble in fats that it can be trapped in emolutions, and so I'd have to say that distilled water maybe with ice would be best.

Hot water actually makes for a hit thats not as harsh, but it's a little bit weird. Cold water also is a good option to make the hit seem smoother.