Depending on where you live, the attic itself, and so on, I think the high and low estimates for either one is about $1.00 - $1.50 per sq. ft. They're about the same price, give or take a little.
If you have exposed soffits in the attic, make sure the contractor doesn't block them (in either type of insulation.) Inspect the job BEFORE and AFTER. Also, don't compress the insulation. It works best being 'luffed' up. Make sure you know where all your wiring is up there before you install. Make a drawing, put it in a zip lock, and TACK it to a rafter near the doorway. It may come in handy some day!