I use this type from petsmart.
Top Paw® Mia Collection Dog Harnesses - Harnesses - Collars, Harnesses & Leashes - PetSmart
I like that I lay it down and she sort of steps into it, then it snaps/buckles on her back. There is no over the head needed. The dividing strap goes between her legs and up her chest. Has worked well since she was a baby.