If you're in the US, avoid using what's typically labeled as chili powder, as it is a blend of spices rather than pure ground chilies. If pure ground chili is not available, you can substitute it with cayenne pepper. I prefer using pure ground chili for making taco seasoning because it lets me manage the flavor consistency better. Chili powder varies not only internationally but also from brand to brand within the US. Opting for pure spices ensures a more consistent flavor profile.