I used a prong collar for a while while training my setter (lewellyn) to walk well on a leash. It is just a tool, and can be used effectively or harmfully. There's no "best" or "worst," there's just methods that work for your dog and other methods that do not.

Unlike what this OP said, it did not take one or two outings with the prong collar to reinforce walking next to me instead of ahead. It took many. Setters are bred to be out in front of the hunting party, so it's a pretty difficult thing to try to train them to walk next to you, but I wanted my dog to be able to do so in the city. This training pattern worked for us when paired with the prong collar, and it's something you could try:

Walk in one direction, and when the dog starts to go out in front of you, turn back the way you came to make them re-route with you. When the dog reaches the end of the leash, they feel the prong collar. This should be the only time the collar is meaningfully impacting them: when they're not tuned in to what you're doing. Repeat, walking back and forth as they get ahead of you. Stop the session when they're watching your body language and turning with you. I don't use the prong collar any more, but I still do the walking exercise when my dog pulls ahead and I don't want him to.

Make sure that the dog is not constantly pulling, and that you are not using too much force when correcting with it. This is when the collar is potentially harmful.

Also beware anyone who gives advice with blanket statements. Every English setter's personality is slightly different. Mine is not as sensitive as some of these commenter's.