The answer to this question is a matter of opinion. Different people have very different opinions as to the relative merits of rehabilitation and punishment. Let us look at the arguments for each side.
On the one hand, we could certainly say that rehabilitation would be better for us. First, it would be better because it would reduce the amount of crime in the United States. With our current focus on punishment, when prisoners leave prison, they are often unequipped to get jobs or to live in society. This leads them to commit crimes again. If we would engage in rehabilitating prisoners, this source of crime would be reduced. Second, it would be better because it would cost less money. Incarcerating prisoners costs tremendous amounts of money. If we can rehabilitate prisoners and keep them out of prison and employed after their sentences, we would save money. We would also get money from the prisoners in the form of taxes on the money they make at their jobs. Finally, we can argue that rehabilitation is a more humane thing to do than punishment. Rehabilitation treats prisoners as important human beings, not as animals to be punished and caged. For all of these reasons, rehabilitation could be seen as superior.
On the other hand, we can clearly argue that punishment is better. The main argument here is one of justice. Prisoners are people who have, of their own free will, committed crimes against our society. Justice demands that we punish them. It would, in this view, be perverse to take people who have committed crimes and reward them by giving them education and training while they are in prison. A second argument is that rehabilitation would not be effective anyway. The idea here is that criminals are criminals because they want to be, not because they lack the skills or opportunities to do other things. If this is true, trying to rehabilitate criminals will not help because they will still be criminals at heart and will reoffend.
My own sympathies are with the idea of rehabilitation, but it is possible to disagree with this point of view.