Planning to upgrade your iPhone this year? If you want the most feature-packed device, the choice is usually easy: You'd buy the latest iPhone Pro Max, and this time around, that's the very impressive iPhone 18 Pro Max .

However, Apple decided to throw a curveball at iOS users this year with the release of its first-ever Apple foldable, the iPhone Duo .

Now, iPhone users have to make a difficult choice. I know because I'm one of them. Before the September iPhone event , I assumed I'd go with the new Pro Max, but the unveiling of the Duo had me second-guessing my decision.

So, should you go with the iPhone 18 Pro Max or the iPhone Duo ? Each is powerful in its own right, as they both have Apple's new Apple Silicon chip A20 Pro.…