It is well known that choke chains used to be the main training tool by professional trainers all around the world. More recently professional trainers are switching to postivite training methods. Why? There is more science research backing that a dog trained by positive training methods is less likely to become agressive or fearful. Choke chains are considered positive punishment in Psychology terms. Animals can be trained by both classical and operant conditioning. Positive means the "adding of" and negative means the removal or taking away of. Choke chains add suffocation when the dog pulls or doesn't do what you want. It is claimed this is the only method to work with large to giant dogs and I'm here to tell you it's not the only method. Air is essential to animals. Lack of air can cause bodily damage including possible brain damage. Does that sound humane? It's really not. It's abuse to choke a child for walking in front of you, yet people believe it's not abuse to do the exact same to a dog via a choke chain. If you wouldn't put it on yourself or child for the same behavior don't do it to an animal.
Other humane methods:
Positive training for basic commands
Positive training professional trainer/classes
The below tools should be used as a training tool to aid with training not a means of a quick fix. It is essential to fix the underlying issue(s).
Martingale collars: when pulled collar tightens but if you pull the leash loop the collar does not go smaller than the width of the dog's neck. This is how you will know what size to get. These collars need to be properly fitted.
Front lead harnesses: when pulled dog is auto corrected to face you.
Command collars: when pulled a sensation similar to one their mothers provided them with as pups is felt. The difference between this collar and a pinch collar is less ability to turn the collar into a punishment tool and rare occurrence of causing any damage to the dog. The command collars have a triangle plastic link linked to many other triangle links with a martingale style leash connecting rope. This collar must be fitted properly in the same way as martingale.