My puppy wears a harness as he sumtimes pulls when out walkin ...?

We brought the first one in a rush as we were worried of injury But now I have seen a really nice one but expensive Before we buy this I just wanted to get a few opinions Is it a good idea to keep with harness or do u think it makes them pull into it ? Also Ive seen a leash that goes around the dogs nose which is also meant to stop pullin I would much rather fix the problem (we have just started obedience cles) and have him walk on just a collar and leash But he is a staff X and very strong so is a nice comfortable harness best ?