Although each person's set of taste buds seem to respond differently to each brand of Stevia, here's my impression.  Stevia Supreme by Stevita was the most bitter, a truly unpleasant and long lasting after taste. I threw it away. Sweet Leaf had a strong chemical taste, as well as being quite bitter. It immediately joined Stevita in the trash bin.. Now's Stevia was not bitter, and not bad tasting, although it had an odd flavor overtone, perhaps a bit nut-like? It would take a wine connoisseur to properly describe this flavor. I did keep it.