Which is better - blown-in or batting insulation for attics, and what type of...
That is a close call. The batting insulation is usually fiberglass and resists settling, but has a slightly lower insulation (R) value per inch of depth/thickness.
The blown-in is usually a paper product that does settle a bit over time, but has a higher initial insulation (R) value. With the settling after a several years it probably ends up about the same R value for the same depth as the batts. The paper products are treated for fire resistance so that is not an issue.
The blown-in paper product nearly always has a good price advantage, so that it is usually the product of choice.