The OnePlus One if only because it debuted this year and is an outstanding device for the price. I can definitely see the Moto X though, too, although I'd equate it more with 2013 and it would be vying for the title with the Nexus 5.
The Oneplus is a nice device for a decent price BUT it has zero customer service after the sale and many have serious hardware issues with their unit. Just take a look at the official Oneplus support forums and you will see what I mean.
I think the Moto X (2014) is a contender for top phone but it looses points for the battery and camera. I don't think there is any one phone this year that's #1 as they all have some sort of shortcoming.
- Note 4 = Gorgeous screen, long battery but it has TouchWiz
- Oneplus = Nice screen, nice price but support is non existent and it has hardware issues
- iPhone 6 = Great build quality, long battery but only a 750p screen, 1GB of ram and you are stuck with iOS
- Nexus 6 = Nice screen, average battery life but it's GINORMOUS
- LG G3 = Great screen and good battery life. Many don't like the buttons on the back (me included) and I found the camera to be average. Not a fan of the LG logo on the front of the device.
- Moto X (2014) = Premium build, customization of your phone and almost pure Android with a few awesome Moto features. No wireless charging and battery life and camera set it back
These are the phones I've had in 2014. I've not had a Z3 so I can comment on it. I do have a Nexus 5 but left it off the list because it's not a 2014 device. The Nexus 5 is still among one of the better device out there and for it's price it's still hard to beat..
My Cyber Monday Moto X was sent back because of very bad pink tinting on the screen. My replacement should be here next week. Moto customer service was horrible and would not, or did not know, how to give me another code to order. I found another code here to use so I'd also say customer support is another negative when it comes to the Moto X (2014).