I'm on 9.2, and not having battery issues. But, it's like I keep saying. It's mostly in your settings and what you do on the phone. I just try to enjoy my 6s Plus. I'm not going to watch the % indicator and worry myself over battery. It does fine.
Here's a battery test. Do this test. If it passes the test, then it's in your settings or what you do.
The Test:
Write down your usage and standby time, press the sleep/wake button (or lock button, as some call it) to put the device to sleep, and set the device down for five minutes. When you come back, take note of the change in time. If your device is sleeping properly, then the Standby time should have increased by five minutes and your Usage time by <1 minute 3. If your Usage time rises by more than one minute, you have a drain problem. Something is keeping your device from sleeping properly, significantly shortening the time it will last.