Long ago there were several insulation materials available: Rockwool, Vermiculite, Fiberglass, Cellulose, Mineral-Wool, all sorts of stuff. Over the years we’ve seen many come and go; they were found to be dangerous, ineffective or impractical. Today there are basically two choices: Fiberglass and Cellulose. The confusing thing is that Fiberglass is available in two forms: rolled batting or blown, and Cellulose is only available as a blown material. It’s not that difficult to figure out which one is best.