Pretty cool that you used an iPhone 6 for 6 years! iPhones have great longevity, especially if used on their original iOS version. I still use an iPhone 6s on iOS 10 and it is amazing! Battery life is still almost like-new, and even if it doesn’t hold a candle to newer iPhones (or even the plus models on their original iOS versions), performance is flawless. App support has waned, obviously, but apart from that it is perfect. Yes, heavy LTE usage will make battery life untenable, but I don’t use it like that, so it’s fine. It’s my favourite iPhone!