depends what your price range is the ice kool or evakool are both top quality boxes
fiberglass boxes will hold your ice longer than the plastic boxes.
fiberglass boxes do not obsorb as much heat as the plastic boxes
fiberglass does not retain the smell of fish
fiberglass tends to be heavier.
plastic boxes (ice kools) do not reflect the heat as well as the fiberglass boxes
plastic boxes can hold the smell more than fiberglass
i have heard reports of plastic boxes lids warping in the heat.
hope that helps you out a bit