We tried the step-in harness, but it was a nuisance to put on and take off. We couldn't leave it on Penny because she mats easily, and we keep her coat at a medium length.
At the beginning of summer we ordered a vest harness from Tiger's Mom, Des, and we love it. Some friends of ours requested the info and will be ordering one soon, also, as their little one figured out he can chew through the step-ins!
Watch out, though! There is a wide selection of styles, fabrics, and embellishments out there. You might not be able to stop with just one!!
I'm planning to order Penny another here soon!