high-loft batting is polyester- good quality ones do not beard, pill, clump or bunch- some are made for tied quilts/comforters. as long as they are quilted according to recommedations.
wool battings are nice & fluffy/lofty but not as lofty as high-loft poly,
double cotton batts make a very heavy quilt- and the cotton (settles) and becomes very dense-not lofty.