Normally I would suggest to start with just salt and garlic powder, however if you use no salt then you're not boosting the natural flavor of the chicken. Therefore it might be necessary to use a more complex blend of spices to get more flavor. I see no need to add sugar or any sugar substitute in either case.
Do you like Indian food? Some of my favorite spice combinations are rooted in Indian recipes that use things like cardamom, cinnamon, cloves, and cumin. In western culture, we typically only use cinnamon and cloves in sweet foods, but they add a fantastic dimension to savory foods. And just because you're using Indian-style spices doesn't necessarily mean the dish has to be spicy hot, if you don't like that kind of heat. Lamb vindaloo is a great (traditionally spicy hot) Indian dish, but I make it without any spicy heat so my kids will eat it. You could easily adapt this to use chicken and omit the salt and hot spices.
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