A Good Harness
The main characteristic of a good harness is 'where does the leash attach?" In the FRONT on the dog's chest, not the dog's back. A back-clip harness encourages pulling. A front-clip harness discourages pulling.
Sporn HALTER, not harness. The harness is junk. Get the HALTER
Worst characteristics of harnesses
Bought for the color or because it's cute.
Bought for cozy, squishy padding
Bought for Velcro closures
Bought cause it has your college name on it
Clips on the back
Best characteristics of harnesses
Safety. Can the dog back out of it?
Has few features. Harnesses should not have snaps, buckles, handles, or loops. The more features, the worse the product
Is designed to do one thing. Discourage pulling
Leash attaches to the front
The Sporn HALTER is wonderful for dogs with odd-shaped bodies, too. I used this one for decades. The dogs did well, and the owners loved it. I stopped recommending it when the Sporn company stopped making one excellent product and now has an array of junk. If you try this, get the HALTER, not the harness.