No jailbreak on any of them. Iphone 5 crashed on iOS 6 springboard and I couldn't even force restart it, when upgraded to iOS 7 it was the worst nightmare I had, the phone basically shut off for no reason with 60% 30% or 15% battery left. iPhone 6 crashed multiple times while using the camera on iOS 8 (brand new), the performance became awfully bad with iOS, games run slugish, the UI lags and not to speak of the battery issues this phone gave me on since the iOS 10 update.
So yeah my experience with iOS is not the same as many others here.
Those are usually software bugs. Or you had a defective device.
Apple will have you restore and setup as new and if it continues they will replace it.
If you want to continue to restore from old faulty backup files that's on you.