My Nikko hated his harness too. I bought him a traditional one and he would snarl and bite at it. Same went for the step in harness. Finally I bought him a Puppia harness and he loves it!! He gets so happy when I put it on him and he actually pushes his little head into it when I put it on.
Puppia harnesses are really comfortable and soft and come in lots of stylish colors. I got mine from a pet store by my job but you can get them online too. I paid about $20 for mine but it is worth every penny and I will be getting him a few more in case they wear out. Here's what they look like: