Oh dear, these dogs that constantly pull, what a nightmare !!
Some time ago our old chap (who is no longer with us) was a puller, or at least if not a genuine puller he would always put his head down and use his nose, sniffing all the time, this meant he was "leaning" into his collar/lead and causing constant tension (and I hate feeling a dog on the end of it's lead).
I decided to try a "Halti" this was fantastic, initially he fought the wretched thing that was around his face but very quickly he learnt to accept it and walked with his head up an at my side. I was then able to hold his lead lightly and with no tension at all.
A "Halti" is not just a "quick fix" we ourselves need to learn how to use them and fit them on our dogs! When fitted and used correctly with additional training they are a fantastic product. The product controlls the head and turns it inward towards the person holding the lead, therefore completely reducing the ability to pull.
They should NOT be tight fitting and tight under the eye, and I find that the neck strap behind the ears always drops comfortably lower down the neck.
I am by no means a fan of the harneses, I have never yet seen a dog in a harness walking properly at heel, they are always a stride in front or worse still they are still pulling.