I may not be much help but here goes... It depends on how you will be quilting and what look you are wanting for the quilt and how it will be used . If you want as fluffy look, then polyester is what you want. A smother look cotton. But with cotton if you don't wash/ dry ahead of time it will shrink and give your quilt a wrinkled look. I am sure will give you more info, but this will get you started :wink: