I find the radio/antenna on Moto phones are what sets them apart. They get by far the best reception and 4G in places that most other phones are stuck on 3G (or not able to make calls). Also, they get knocked for their industrial feel of the phone, but they are tough as nails and you don't need to wrap it in a case to protect it.
The OS is the next closest to a Nexus for being stock.
The other cool features on this compared to other phones is the always on "Okay Google Now" feature. I didn't think I would use it, but I find myself sending texts, starting navigation, starting music, and checking weather.
Also, these are the only phones that have the ability to unlock your phone with a Trusted Device. This means, you can setup a PIN to lock your phone, but if it's connected to a bluetooth headset, smart watch, car, etc, it goes straight in and doesn't need a PIN to unlock.
I also like the larger screen compared to the One in just about the same size phone. I'm sure there are more things that are cool, but that's what I found so far.