Have used both. While A LOT of Achiote adds a mild earthy flavor, it is a very hard seed and even ground, can have a gritty mouth feel. Both are primarily used give food a bright Color. Achiote is Red on meat and being Fat soluble, turns oil, a deep Yellow/Orange. Turmeric adds a lighter Yellow color, also fat soluble, but not much flavor. Too much Turmeric tastes bitter. If you would like, Post or PM your recipes and I/we would be happy to offer suggestions. There are many combos of spices that give regional or international flavors. Describe what styles of food you like. Indian, Chinese, North African, lots of choices...JJ