If you had to choose ONE of each, what would they be? For me: MOST favorite thing: TouchID. This is my first TouchID phone and I'm constantly amazed at how fast and accurate it is. Effortless operation and genuinely useful many times a day. (But, annoyingly the phone keeps asking me when doing an iTunes purchase to enter my AppleID before I use TouchID to verify...which really defeats the convenience advantage in this case). LEAST favorite thing: power button opposite volume buttons. This is just plain bad design and leads to lots of errors, turning off your phone when trying to take a photo, adjusting volume when trying to power it off, etc.