For those who maintain their innocence after conviction (absolute "I didn't do it at all" innocence), life in prison without parole. That gives the law the opportunity to discover who really did it, without killing a possibly innocent person in the meantime. And if no one is found, the most likely perp dies in prison, without a chance to harm another child.
Unfortunately, there are enough cases of wrongful accusation and conviction in child cases, that we have to be careful about the ones who say they didn't do it. Keep 'em locked away, but give them a chance to prove it was somebody else.
The ones that confess -- string 'em up. The sooner the better.
Those who claim they are "damaged" are right, and almost never turn themselves around. Defense based on "damage" is the same as confession, for child molesters. String 'em up.
We need to take the recidivism rate to ZERO now.