Although Retribution indeed has it's place, after all, one of the main goals of prison is to punish those who broke the law, I believe rehabilitation is better. Rehabilitation recognizes that the criminals can be changed, and deserve a second chance. Rehabilitation can also work when used correctly. An example of this is the Criminon international rehabilitation program, which managed to rehabilitate numerous criminals successfully.
Rehabilitation typically allows offenders to rejoin society as productive members of society. Retribution merely forces them to languish and atrophy in prison for the duration of their sentence. Surely, this is both a waste of resources and a tragic loss of an opportunity. Why not help them turn themselves around, instead of doing nothing and letting them out of jail just as embittered and likely to recidivate as they were before? And, if they are rehabilitated, hasn't society recouped on its investment of rehabilitation? I think so.
In the U.S. Criminal Justice System, rehabilitative justice is a nice idea, but it is expensive, and it seldom works. The studies show that rehabilitation efforts have little impact on the numbers that actually recover and change. It is not society's job to change people. It is only their job to hold people accountable.