Definitely the 15 plus over the pro max. I have a 14 pro max and everyday I wished I had just gone for the 14 plus. I think most people do not need the pro models. For what the iPhone is used for in the lives of most people, the variant is definitely enough. You will get use to the 60 refresh rate in no time and the pictures you take will almost certainly be enough with the cameras of the plus variant. I really hate the fact that Apple makes 4 variations of the same phone. I really wish Apple would go back to the days of just making two var, the regular phone and the plus phone like they did for years up until the iPhone X. Back then you had the regular model and the plus model. The choices were a lot easier to make.

Get an older one and for your son, I imagine a plus model might be the right choice.

I know android users like to customize their phones and make it their own. For me, though, it is the simplistic nature of iOS. I do wish Apple would let users customize their software to a certain extent more than they allow and I really, really wish Apple would add in screen fingerprint scanning to their phones. Those are literally the only two things I wish Apple would invest more time and energy into. Other than those, it is the consistent updates, the simple software, the mostly reliability among my reasons for sticking with iOS.

If you use google voice, you can screen calls by having the person say their name before you answer so you know who is calling.