Niether, put the money in the bank and use it to pay for any repairs that would be otherwise covered. Chances are, you will have money left over in the end, possibly a lot of money if you are a little lucky. After all, extended warranties are not a favor, the vendors are making HUGE profits on them, as is the dealer.
Just like Vegas, the house always wins...
'11 328! Touring - Tasman on Chestnut, 6spd manual, factory upside-down "i" option