I prefer cotton battings to polyester, I haven't used polyester in years ... but it all depends on how you want your quilt to look. I like the flat, antique look so I use cotton in my quilts. Some people like a thicker, puffier look. Cotton batting is usually best for machine quilting but the 80/20 blends are good too. I like Quilters Dream, Warm & Natural and Bamboo is wonderful ! There are so many choices today, you can find just what you need, for the way you quilt and look you want. :)