I currently use nylon harness on Mason but lately I've been noticing that after our walks, his skin gets so red from the friction of the nylon against his skin/coat. I have not tried the vest harness, but I recently purchased a step-in-harness and leash (in one) that you can just put your dog's feet into, pull up the harness, tighten at the back, and that's it. No buckles or belts. I saw someone using it on her dog one day in the park and it looked so easy to use and so convenient (it slip right on and off).
I bought at glamourdog.com and here's the pic of the harness
http://glamourdog.com/caonepistinh.html
I haven't gotten it yet but I will let you know how it works out!