I have used the Puppia step in vest harness for Gracie since she was 6 months old. She was a puller at first and we never had a problem. I only take her out on a leash and that is the only time she wears the harness. The velcro does need to be adjusted so the vest is snugly against the body before closing the top clip.
One time after a walk I did not take the harness off right away and she started to roll backwards on the floor and got it to slide up toward her head. I don't advise leaving a harness on except while walking the pet.
The buddy belt is a good harness but kind of expensive for a puppy that is going to grow out of it. The Petco harness is much like the Puppia vest harness though sizing is different.
There is a harness that is kind of like the buddy belt but a bit less expensive. The sizing is different also.
Choke Free Step-In Harness for Small Dogs