I buy batting depending on the look I want. If I want a crinkly look when done, I buy Hobbs 80/20 blend. If I want a smooth look, I buy Hobbs Polydown. The one variable I always have to consider is the quilting distance....as a previous poster stated, it will vary from batting to batting....I do all my own quilting by machine on my 6600 and neither cotton or poly make a difference in difficulty for me. Opinions on batting will be as different as "what machine is best to use", so take it all in and choose what is best for your particular situation.