I develop for iOS. I want the iPhone 7 because 3d touch would be nice to develop for. It's probably the next feature that will be standard on phones, but it's going to be a while before developers make apps that actually use it. If you're buying a new phone, I recommend 6 or 6s, whichever you can get at a low price. There's really no point to buy the newest iPhone if you can get one relatively new with the latest iOS update, iOS 10