The sweetness in stevia is very different from sugar/hfcs... it has a flavor of its' own and is somewhat off-putting if you aren't used to it. Using a mix of sweeteners is often better overall flavor than any single sweetener (stevia, aspartame, ace-k, etc) on its' own.

I really wish Coke Life had better marketing and was more popular... It was a much smaller amount of real sugar combined with stevia for sweetness. It was lower calorie, but not zero, and probably a much better option than either full sugar or zero sugar.