My preference in artificial sweetener's is Stevia. Although I have tried others, Life Brand Stevia is my favourite.
It's from natural extracts and no chemicals .There's no aftertaste and I love it in my coffee.

Stevia.
I've tried different brands, but so far have settled with life brand, it doesn't have an after taste.
Seems to work well.
You don't need much and the packaging works exactly as measured too. 0.6g.

It's natural plant extract.