Hi Gus Gus. That depends heavily on the breed and size of your pup. If you can share that, I can give more specific recommendations. Meanwhile, we have an article covering the best dog harnesses for running. We have winners by best value, most popular, and best for tactical. Our buyer's guide covers safety, adjustability, comfort, and durability.
Have you looked into Ruffwear brand? It has everything you could possible need for running gear for your dog (harnesses, running belts, leashes, shoes, safety lights, reflective jackets, etc.). I just saw the brand for the first time when I was shopping at REI, and everything seemed to be excellent quality.