the thing about diet sodas is the kind of sugar. i tried coke zero and thought it was pretty good. i was really surprised. i don't like diet coke, prefer diet pepsi.
my sisters came to visit and we got some pepsi max. it's ok, but as far as being an energy drink, i don't really think it was.
they also say if you are trying to be healthier that having a sweet soda (reg or diet) helps keep your body craving sweetness that can't be achieved in natural foods (fruits mostly).
the acid can eat the enamel... i'm sure you've seen where you can pour it in your toilet or on your windshield to get rid of the "haze."
i only drink 2 sodas a day, so i think i'll be fine