First, let me say that I am a very particular iPhone buyer so take what I say with a grain of salt.
I. Screen size: I know that the air is 6.5 and the promax is 6.9 but just knowing that there’s a phone out there with a bigger screen would annoy me every time I looked at my phone
2. Battery: I know many people on here are saying that the air and the pro are similar when it comes to battery, but for someone coming from a promax, my battery life would be sacrificed. I have lived with battery anxiety before and I wouldn’t want to go back.
3. Design: I know many people believe the air is the best looking of the pair but for me, I appreciate the design of the pros. Like my Apple Watch Ultra, I much more like the industrial design.
But again, I may not have to same concerns. Pick the phone that serves you best.