we are using prong right now
My dog is just over a year old and is crazy strong. We have been going clicker training on loose leash walking. Which he was doing well with on all things, but walking. He would be fine and then yang my arm off trying to change directions to go to the park, or go sniff another dog. Sometimes he would just want to go down a certain street for no apparent reason and it was very tough to hold him back. No amount of clicking and yummy treats seems to stop this or help him figure it out. We never had this issue with our previous dog.
I first tried a martingale collar because it seems less intense, but like the choke collars, it just seemed he would be in a permanent weezing choke for blocks and blocks as he pulled. I was starting to dread walking him and I really love walking and exploring neighborhoods.
My brother swears by his prong for his boxer, so I broke down an bought one. Walking is now a pleasure, we stays by my side or in acceptable loose leash-ness. I've been using the clicker and treats too in the hope that we won't always have to rely on the prong collar.
My main objection to the prong, besides the 2 collars issue, is that non-dog people interpret the aggressive look of the prong collar to mean your dog is mean and out of control. With a mostly black GSD male, we don't need anything else going on that contributes to people being scared of him.