QUESTION
Which iPhone is best: the 13, 14, or 15?
Best overall: iPhone 15. It is the best pick of the three for most people because it has the biggest practical upgrades: USB-C, Dynamic Island, a newer main camera system, better long-term software runway, and newer hardware.
Choose iPhone 14 only if it is meaningfully cheaper than the 15 and you do not care about USB-C or Dynamic Island. Choose iPhone 13 only if budget is the main priority and you find it at a much lower price, especially refurbished or used.
Quick verdict: iPhone 15 > iPhone 14 > iPhone 13 for most buyers. But value depends heavily on the current price difference.