We have tried alsorts of substitutes, I'm the baker, my husband has diabetes.
Every sweetener used has tasted rank, to both of us, and leaves a foul aftertaste
BUT, the ONLY one I would recommend to any one is Hermesetas liquid, it is great.
There is no aftertaste, and the guide is to use one teaspoon/ 5 ml of liquid = 10 teaspoons of sugar(approx 50g sugar)
It comes in a clear plastic bottle with a blue lid and a blue label, a 200 ml bottle will last ages if just using for baking, I have to order it from the internet though as I can't find it in any supermarkets, so just before you throw in the towel, try it,
Regards Maddy