I upgraded from and HTC One M7 to an iPhone 6 Plus. I miss a lot of the features and customization options available with Android, but the iPhone has never let me down. While my M7 became slower and slower and exhibited glitches at it neared 2 years old, my iPhone has been noticeably less finicky. The latest iOS update has slowed it down a bit, but it works. I don't need to reset it or wait for extended periods when multiple apps are open - it just works.
I'm hoping I don't need a new phone for at least another 2-3 years.
I honestly still want to go back to an Android phone, but it's tough to do so when my wife and the majority of my family have iPhones. My mom just got an iPhone and FaceTime is much easier for them than other apps. They can literally click on our contact info and then press the FaceTime button to initiate vidcom.