I think the big problem with the choke style collars is that many times they are not put on correctly. So instead of just doing a quick pinch and release, the chains stay too tight and can bruise the dog's windpipe.
When used correctly, they can be effective training tools.
Agreed. When I went to obedience class, it was required and step one was learning to put it on right. They don't harm the dog if they are the right size and are put on properly.
When I walk my dog, we use a harness. The choke collar was only used for class purposes and to teach the dog tasks, as a nylon collar won't do the same thing. Gentle leaders are great for some dogs, but not for others. I was recommended to use a chain collar that was weight and size appropriate.