Your quilt is lovely and I don't think you could go wrong, either of the choices you presented are nice.
If it were mine I would have made the border wider and close to the darkest color in the quilt to frame it out and then do the piano key and a binding of the dark color. If I use a color that is much darker than my quilt fabrics I go small with it and then add another border similar to the quilt colors and frame it in the same dark fabric.
You will have as many different ways to finish it as you have people but it's your quilt and you know what you like. I often see quilts with fabric choices that just aren't my choices and I love them.