I can only spend up to ?550 on my new iPhone and the iPhone 6s (?539) and 6 Plus (?539) fit this perfectly. However I'm so stuck on which one to buy, I thought I wanted a bigger screen and mammoth battery as I'm coming from the Note 4 however I want the latest and greatest and I feel the screen and battery life will be fine for me as I mostly watch videos on my iPad and need the phone to last through the day with medium usage. Thoughts on which one to buy?