They have the best extended warranty coverage. Your phone has Applecare for one year. American Express doubles the warranty if anything is to happen to your phone. If anything does happen, they will refund you the money you spent on the phone if Apple won't in most cases. Consumer Reports says that they have the best warranty policy and fastest reimbursement. Note that they will only refund the price you pay for the phone, so if you bought an iPhone 7 32GB for $199 subsidized, they will only refund that much. If you pay full retail, they will pay that price.
There is also purchase protection:
Purchase Protection is an embedded benefit of your Card Membership and requires no enrollment. It can help protect eligible purchases made on your Card when they're accidentally damaged, stolen, or lost, for up to 90 days from the date of purchase. Please read important exclusions and restrictions to see if your item is eligible for coverage.
There is also purchase protection:
Purchase Protection is an embedded benefit of your Card Membership and requires no enrollment. It can help protect eligible purchases made on your Card when they're accidentally damaged, stolen, or lost, for up to 90 days from the date of purchase. Please read important exclusions and restrictions to see if your item is eligible for coverage.