Switching to AT&T Cellular: Any benefit in buying phones? How to get a deal?

I’m looking to switch to AT&T for cellular service. I will need 3 smartphone lines and 1 Tablet line.

All of my phones are unlocked and work with AT&T.

I will probably be buying an iPhone 15 Pro Max before I switch.

Is there any benefit to buying the iPhone from AT&T, whether financing it or otherwise, versus just buying it from Apple?

I don’t really care about financing. I’d just as well rather buy it outright from Apple, but if there is some kind of an incentive to buy it from AT&T, I’d be fine doing it that way, too.

They make it so godamn convoluted (probably on purpose) to see what’s the best plan configuration to pay the least amount of money for the service you want.

Shop around! Amazon / at&t / bestbuy and find out who has the best deal for ya!

Edit: And if you let them know your getting new service with at&t they may have even better deals for ya!