That depends on the user and the environmental risk level of the wearer.
More Detailed Answer:
First, assess the type of threat you face on a daily basis. Review data from shooting incidents in your area, as well as the types of weapons (firearms, knives, etc.) being confiscated from suspects. Also factor in what type of sidearm and duty ammunition you are carrying; FBI Uniform Crime Report (UCR) data indicates that approximately 1 in 6 officers that are killed in the line of duty are shot with their own weapon. Other considerations are: the climate in which you work, typical duty assignment, and personal preference considerations (comfort and fit). Again, the decision is ultimately yours. The same concepts apply for correctional officers seeking stab or puncture resistant armor.