A couple questions. Do you use the attic for storage, or use as a bonus room? If neither, I would use a R-15 or better pink insulation, attaching the tabs to the would with staples. The point of insulating, is to create a barrier to keep the heat/cold out. The pink is the best bet. An alternative, is a plastic piece they make that creates a void between the attic and the roof, so that the heat rises wot he top, and out the vents. It helps prevent condensation in the attic.
A builders supply place should have what ever you need. Home Depot, Lowes, ect.