Why did groups resent the Aztecs?

The Aztecs were an imperial state that had conquered numerous other local tribes. From these conquered peoples, the Aztecs demanded human sacrifices so that they could appease the Aztec gods. The constant forced tribute of young men for sacrifices angered these tribes mightily. As a result when the arrival of the Spaniards changed the power dynamic and allowed them to rebel against the Aztecs, they took the opportunity, not realizing that they had simply chosen a different demon.