DPA and choice of feedback ?

Do not have an app note or other material comparing the advantages and disadvantages of different types of feedback?

 More precisely my point about the choice of feedback at DPA families.

 let us source

V in 16-35V

Output power min 0,1W  up to 3W , if temperature descent 0C consumption rises up to 17W,

Working temperature -20 +50C.

Requirements:
-max reliability and durability
-max efficiency

 How to select feedback  zener diode on Primar or TL431 on secundary?

 I am inclined to the zener primary because I optocoupler come as long times unreliable component with considerable consumption but I'm not sure what your options