Nutmeg, think of how a puppy's mom picks it up--by the neck. Dog's necks are pretty tough, so regular collar use doesn't hurt it. The chain collars are okay in the right hands but if the owners snaps and yanks at the collar, it can damage the dog's trachea. Much better are the martingale collars, which have a bit of chain at the top where the leash attaches, but not underneath.
When a dog is pulling and straining against the collar, it means they haven't been trained to walk on a leash well. Some dogs are very hard to teach to not pull, especially hounds like someone said (always sniffing), and young energetic dogs that just want to GO. So for those dogs, the NEW kind of harness, where the leash attaches in the front on the dog's chest, are very effective. These are called Wonder Walkers or Easy Walk harnesses. The old kind of harness, where the leash attaches on top, give you zero control. These were invented for bloodhounds and tracking dogs, so that they COULD pull you along. With either harness, you have to watch for chafing.
In my experience a lot of dogs hate the "gentle leader" leashes that go around their snouts. These can also be pawed off fairly easily if the dog is agitated, and a dog can still pull surprisingly hard if they want to. But for some dogs they work well.
I walk dogs at the city animal shelter so I think I've used everything that's out there. We get a lot of dogs that are untrained, big and very energetic. Like, someone got a lab puppy because it was cute, put it in the backyard for the next 10 months, then decides it's too big and unmanageable and brings it to the shelter. Yay! 80 pounds of dog that doesn't know what a leash is! The easy walk/wonder walker harnesses really are the best in that circumstance--this is what we use most often for difficult dogs. Though there are still those challenging dogs that manage to pull with these too!