Moto X 2013, upgrading to the Nexus 6P for...
Immediate OS updates,
Android 6.0,
Google Fi and cutting my monthly phone bill by half,
Better battery, camera, finger print scanner, and pretty much everything hardware wise.
I will admit that I'll miss the custom Motorola software, the phone silencing itself at night or when my Google Calendar shows that I'm busy, reading me texts while driving, and launching the camera with the twist of the wrist. I was going to go for the Moto X Pure, but the overall Nexus experience was just too much to resist.