I'm using 2. I tried 1 for awhile but it is too soft for some situations. I'm coming from a Nexus 6P, so I'm not used to a "button", the Touch ID on that phone is merely a sensor -- and I'm also having to adjust to it on the front rather than the back. Two feels the most natural to me; I have an iPhone 5C as a spare, and 2 reminds me of the home button on that phone. As for the new home "button" as compared to a physical button: I'm ambivalent, maybe slightly prefer a physical button -- though that could change once I've had the phone longer.
