Personally, I think I would favor providing something like food through a system like food stamps first. It provides less risk of the money being wasted on addictions (drugs, gambling and other bad financial decisions) and better ensures the money is used to help someone (especially in the case of children, where they are not spending the money, but their parents are).
But part of the theory behind Basic Income is that people will change their behaviour when given more Agency, restricting what they can spend it on doesn't let us test this.
Personally, I think I would favor providing something like food through a system like food stamps first. It provides less risk of the money being wasted on addictions (drugs, gambling and other bad financial decisions) and better ensures the money is used to help someone (especially in the case of children, where they are not spending the money, but their parents are).