I agree that it becomes a personal choice...I would suggest trying several different kinds and see what you like best. It could be one is better for each quilt choice you like. I love the old wrinkly look that cotton gives and I don't like big and bulky quilts...so my choice is easy...low loft cotton. But I would consider using poly if I wanted to quilt it to have a puffy look in certain areas of the quilt. As you look at finished quilts on this board you will see how they vary.