I've now tried pretty much every kind of Zevia cola, an all-natural zero calorie soda. It is sweetened with stevia, rather than aspartame or sucralose. None of them is overly sweet, as I find with most diet colas, and I feel the stevia is better for me. I've narrowed it down to my top five.
5. Orange doesn't quite match the flavor of Stewart's (regular or diet), but it doesn't have harmful sweeteners in it, either.
4. Ginger Root Beer tastes like an old-fashioned, bottled root beer.
3. Lemon-Lime has a fairly unique lemon-lime flavor; I like it as well as any diet lemon-lime flavor out there.
2. Ginger Ale is similar in taste to diet Canada Dry, to the best of my recollection. I haven't really used aspartame to speak of for about 10 years.
1. Black Cherry. This tastes nearly as good as Diet Rite Pure Zero Cherry Cola, but doesn't have Splenda® in it.
The only downside is the cost. (Regularly priced, it's about $1 per can for a six-pack.) The lowest price I've been able to find a six-pack in stores is $4 each when it was on sale at either Whole Foods Market or The Better Health Store. When I buy only one at the local health food store, I don't pay much more than I'd pay for a can of pop at the gas station.