I am afraid that both are wrong. I have been told by some very good Milongueros, that you never step with the toe or the heel, but instead step on a flat foot. The toe and heel must meet the floor at exactly the same time, much like the way that a cat steps. This will give you the smoothest gait and the follow will barely feel anything except for a smooth glide. When you reach the perfect equilibrium with your completely flat steps, it will feel like you are dancing on clouds.
BTW, have you ever seen a cat land on anything other than the ball of it's foot?