I think it depends on the dog. I have a cavalier that I put smaller/thickness collars on. Also, some people feel small dogs (esp. cavaliers, chihuahuas, dachsunds) should wear harnesses. For a big dog, I would put a wider, stronger material so that they couldn't pull. A lot of bullie type dogs are very strong, so their collars are thick and most of the time made of leather. Sight hounds, and other dogs that have smaller heads than necks need martingale type collars so they can't back out of them. Some dog's tracheas are more susceptible to damage (like greyhounds, chihuahuas, etc.), so a softer and maybe wider collar might be of some help. I do think it depends on the individual dog. My favorite collars for my other dogs are limited slip collars in about 3/4" thickness.