I was debating on February this year whether to buy a 5s or a 6. Several things favored both phones (for the 6, that it was the newest one, it had greater battery life, and the screen was better, for the 5s, mainly portability and ease of use.)
I ended picking the 5s, and the only thing I would like a little more is some better battery life. I do not care about the rest, although I did not regret of my decision. I do not think also, considering what I've read, that the 6's battery life is much greater than the 5s. I am delighted by the plus's battery life, but that was out of the question due to size. That thing has a battery life similar to the iPad!!!