I have had commercial versions of both from I believe was Whole Foods last time. I have tried both a few times and didn't care for either. The keifer was more palatable of the two. I was introduced to it overseas. I may be forced to change my ways one day, but, for now I will stick with the lesser of evils.Have you ever tried homemade water keifer or Kumbacha? It's a process to undertake, but the resulting beverage is worlds better for your body than any carbonated drink, sugar-free or not. Both will carbonate a drink and are quite tasty. Although there is some sugar in these drinks, they provide a ton of beneficial probiotics in them. There are commercial versions of them too.