For a puppy, I would definitely recommend a harness, after Shadow slipped his collar a few days after we had brought him home. It could have ended in an unthinkable way. I ordered harnesses immediately. They are also far better for their throats. Puppies can't be expected to know not to pull, and can do a lot of damage to themselves when all that pressure is focussed on a thin strip of fabric. I would recommend a mesh harness for a young puppy - I used the Puppia ones, like in my avatar. I prefer to not use the front ring at all, and train a loose-lead walk and walk to heel that doesn't depend on mechanical corrections. The front ring would just be used for "emergencies" where I need to get somewhere in a specific time frame, the dogs have started to pull for whatever reason and I don't want to destroy the work I've done so far on LLW.