It is wiser no matter how you put it, even if the scenario favors highly on buying a new iPhone, the wisest choice will always be to invest in it rather than buying a phone. Phone is a depreciating asset and you don't want to be caught in that part of it's life cycle, be content with the flagship but cheap phones on the market if you really need a new phone but other than that, invest money for the future, you're better off having money in the future rather than not knowing where you will get your next money. It really offends me when people ask me this kind of question and then they try and justify the wrong choice, if you justify the wrong one then you should've never asked for advice in the first place and you should've chosen to get the wrong choice in the first place.