floor insulation

[vsquared]

I am trying to figure out what is the best insulation to put below a floor with a crawlspace. I am putting a floor over an existing poured concrete slab from an old garage. The wood framed floor ,2x10 construction, with 3/4" tounge and grove plywood is suspended approximately 12" from the concrete slab. The room is approximately 22' x 21' . The crawlspace is too small to do anything with. Is it better to use traditional fiberglass insulation between the floor joists or would it be better to fill the deadspace between the concrete floor and the sub floor with loose fill insulation. And if the loose fill is better should it be filled to the bottom of the floor or would air space be required. I believe the insulation is R19 but Im not sure of the insulation of the loose fill.