If you bought an iPhone Mini or an Air, but that model is gone at T+3 years, that's a lot more likely to result in you looking to Android, than if you bought an iPhone 13 and want to upgrade to an iPhone 16/17.
The iPhone air has a 6.5" display. That's bigger than the base iPhone 17 (6.3") and the iPhone 17e (6.1")
You're probably thinking about the thinness of the phone. iPhone air is 2.4mm thinner than iPhone 17, but I don't think anyone is asking for that, as most people use a case which makes the phone thicker.
But the thinness isn't actually the appeal. The key thing is that it's a lot lighter. (And yes, a case adds weight as well as thickness. But if you start from a lower baseline, you still end up in a lower place.)