I understand that "Deal breaker" is an expression used for a feature/characteristic that would make one not go for a deal (or terminate a contract), even if the deal's other features are great.
What expression would be the opposite of "Deal Breaker"? I'm looking for an existing expression that would describe a feature that would make one go for the deal, even if there are other not so great characteristics.
The expression could fill the sentence below:
I know this phone carrier has higher rates and everything, but if they are offering free iPhone to us if we switch, that would be a
<expression here>! We would totally go for it.