I would argue that both of these types of sentencing have their place. For less serious crimes, it seems that "personalized" punishment would be appropriate. But for more serious crimes, more structured sentences seem appropriate.
"Personalized" punishment is more appropriate for instances in which the judge thinks the convict can be rehabilitated. This should be applied in cases like minor drug case, burglary cases, and other such non-violent crimes. Such sentences might help to rehabilitate the offenders and prevent them from moving on to more serious crimes.
Once an offender has committed a more serious crime, structured sentencing should be used. A person who has seriously harmed another is not a good candidate for alternative or "personalized" sentencing. Such people are too dangerous to make the risk worthwhile.