IMO, putting a prong on a puppy is like using a hammer to kill a fly. Having said that, any collar can be a weapon in the wrong hands. Prongs make me uncomfortable for the 'average' dog owner that hasn't learned any leash finesse. Head halters are the lessor of two evils imo but again if not used correctly it is a problem.
People always say that they have a dog pulling problem..............what I see is dog's having a people pulling problem. For the most part people teach their dogs to pull, don't have enough finesse to stop hanging onto their dogs and very few people naturally have that skill and that light feel for the leash