Explosive arrows: As you said; like an RPG.
                  best used for AOE/damage multiplier, possibly armor piercer

Combustion Arrow: Use as incendiary and/or anti personnel round

Multiplication arrow: shotgun replacement

Lifeforce Steal: Unless the archer is able to ramp up to truly superhuman
                 speed/strength for a decent period of time this effect is really not
                 worth getting. How many people can one archer kill before someone
                 shoots him or the effect wears off? If it lasts a minute, it is
                 worthless. Lasting a few days might make it worth using.

Cold arrows: Even if it freezes a target into a giant ice cube, how is this better than
             setting him on fire using combustion arrow? A kill is a kill.

Madness arrow: How long does effect last? Does the victim go catatonic or does he attack
               his own side? The effects matter when deciding.

FaZe Arrow: This arrow can bypass Armor and walls. the only downside appears to be
            aiming through armor or walls.

Hunter arrow "follow the target...will maintain...maximum speed until Target is hit":
              What a great anti-aircraft round! Aim it at a pilot in a jet.
              30 minutes later it catches up to the pilot walking across
              the tarmac and kills him.