We bought the small for our miniature dachshund Stevie. She's been okay with the overhead harnesses but we wanted something a bit quicker and easier for a short walk so this was a perfect choice. It's been really easy to clean which is important for a sausage whose belly is so close to the ground!
We have chosen strap harness before as we were really conscious with other chest harness that they would rub in her armpits/behind her front legs but we've done a walk every day with a week with no trouble at all!