If your dog doesn't pull, a collar is great. Some prefer it if they use leash cues (gentle pressure in various combinations to convey different commands, like heel or sit) because the dog feels it more, though I personally have found that my dog feels it on the harness just fine. If your dog pulls, though, having a collar on could cause throat problems, so you should use a harness, at least until you have finished training. Also, if you use a long-line, you'll need to use a harness to prevent severe injury if the dog runs to the end of the lead. It's a combo of personal preference and practical application.I'm currently using a collar for my lab. Am I being a bad parent for not at least trying to use a harness? My wife has been complaining at me for a while on this, so any feedback I can reassure her with would be helpful .