I traded my 15 Pro Max in for the 17 and I'm happy with my decision. Let me give you a short comparison of pros and cons:
Pros:
1. iP17 got much better battery life (Apple listed iP17 got 29 hours of battery life, whereas 15 Pro Max got 30 hours).
2. iP17 got better heat dissipation.
3. iP17 got a bit thinner screen bezel.
4. iP17 is lighter.
5. iP17 got square sensor for the selfie camera, so you can take landscape pictures without having to rotate your phone.
6. iP17 got longer software support.
7. iP17 got support for the new Photo Style & Audio Mix features.
Cons:
1. iP17 doesn't have a telephoto lens. iP15 Pro is much better in this case.
2. iP15 Pro got a better microphone array. If you record audio a lot, iP15 Pro yields much better audio quality.
3. iP15 Pro got LiDAR, which is essential if you need it to measure or scan stuff with precision.