People ask me for specific product recommendations often. Here are some of my favorites, and they are affiliate links:
Ruffwear Front Range - clip your leash to the front ring if your pup pulls often or pulls hard. Comes in one of the smallest sizes. Padded. Easy to put on. Pads under the clips so you can't pinch your dog's skin by mistake.
Freedom No Pull Harness. Martingale back clip prevents slipping out, front ring good for pulling. Can get a leash they sell that clips to both at once if needed for city walking. Velvet belly band good for thin skin/little fur.
Balance Harness. Great shoulder mobility. Comes in one of the largest sizes.
So how do you choose? Measure your pup and make sure there's a size that gives you a little wiggle room on both sides for weight gain and hair loss after grooming or shedding or shaving. Then consider pricing and your favorite color. When it arrives, make sure the straps make a v-shape over your dog's shoulder and don't restrict motion as he walks or runs.