Typically if the quilter is new or has not mastered the binding part of quilting, I recomend they use the same fabric as the outer most border. This helps to blend the binding with the outer border and imperfections are not nearly as noticable.
If the quilter has done bindings , and is confident , I typically would suggest using a fabric that is with in the quilt. ( I do like darker , for practical reasons, ..dirt) .
I also like to rely on blenders when using a fabric from the quilt is not an option. That being said I do very skinny bindings, so prints just don't show up well.