You would probably be much better off with the rigid foam board.
Also: Lowe's carries a really good garage door insulation kit with foam panels which have a nice white plastic skin bonded to them (the side which would face the inside of the garage), and on the back side the foam is scored (really, dado'd) so that they can be bent along the horizontal, and will pop cleanly into the cavity of the door panel....I installed this kit on a family member's garage door and it came out surprisingly well....installed fast, too. Highly recommended.