Back fingerprint sensor is so much more useful in most situations. I owned the Nexus 6P and it feels like a downgrade to have to use the front fingerprint reader on the Galaxy Note 7, because the way I have to hold the phone. With a fingeprint reader on the back, you're able to quickly unlock in the same manner you normally hold a phone. Yes, I understand there is that scenario where you're at your desk, and your phone is on the table and you just wanted to check the time or do something on the phone with one hand. A fingerprint sensor on the front would be convenient there; however, for me it's a worthwhile trade-off, as I normally hold the phone in my palm when I use it anyway for anything that requires typing or clicking around.