The 6S is faster than what you'll ever need, and for the price of the 32GB iPhone 7, you get the 128GB 6S, which is huge. But if you want the better camera and battery, the 7 is the way to go. I'd go for the 6S, since the camera is still excellent, and I don't think the battery life will be improved so much in the 7. However, the better option here is to wait 1 or 2 weeks to see if there is much improvement in battery life (I'm neglecting camera here, because I think that the 6S camera is more than enough for most people, including me), since iPhones have a bad history with battery.