When making plain nut milk (mostly almond milk in our case), I never use a sweetener.  It should be enough to normally top it up with berries, add Sugar-Free Strawberry Jam, sprinkle it with nuts, or use cinnamon or Sugar-Free Keto Sprinkles on top.  That is more than enough for me and my family.  But it is really up to you. If you use any of the sweeteners, I would suggest either mix Erythritol with Stevia or use already pre-mixed sweeteners such as Lakanto or Besti. That will give you the exact sweetness you are looking for. For our keto chocolate Chia pudding recipe I have added sugar because of the cacao. In this recipe, I have used pure unsweetened cacao which is a pretty strong tasting without a bit of sugar sweetener.