Gentle Leader Collar or Harness How to Choose
Now with the harnesses you will have the leash connection in the middle of your dogs back instead of around the head. Now some people might like being able to have that connection to the dogs back, but I personally like having control of the neck because if you have control of the neck then you also have control of the head to. The other negative that I have found with using harnesses is that if your dog is anything near an escape artist he will manage to get out of the harness, all of the dogs that I have had in a harness have managed to get out of them no matter how I have them tightened. The other drawback is that if your dog is on a chain outside and takes off running and snaps themselves with a harness on it can hurt the back. I know that is what happened to my Lab and why he has back issues now at least that is what the vet told me. The plus with a harness is that your dog is allowed to have free reign with his head.
The other type of collar that I have used in the past while training my dog is the gentle leader. Now the gentle leader you will want to watch the instructional tape or have a dog instructor show you how they work. The gentle leader works best while training and gives you full control of your dogs head because the attachment part of the leash connects around the mouth. The leader does allow your dog to still open his mouth and eat. The negative is that you have to have some sort of guidance on how to use the gentle leader otherwise you could end up hurting your dog or yourself.
So choosing the proper style of dog collar will help you train your dog. You have many choices, but one a couple of them will work out best for your dog. The gentle leader will give you total control of your dogs head and like you have probably seen where the head goes the body will follow. The harnesses will give you control over some of your dog, but not total control and you have to be cautious while using a harness.