I think it really just comes down to your budget and what you're willing to spend right now. 15 Pro Max's camera and battery are fantastic -- I own one and am very satisfied. If you've got the money I'd say go for the Pro Max. You did say you'd rather not do this, but since you're on the 15 series already I think it'd be wiser to wait. Once the new phones drop in September, the previous ones get price cuts from other retailers. Also, carriers usually have good deals with the new iPhones every year so that might be worth waiting for. Whatever you decide, you're getting a great phone!