You do realize that is not the 2014 Moto G, right?

And the HTC Sensation has a lower bezel that measures 16.0mm's.
The Moto G '14 has a lower bezel length of 13.6mm's.
So it is close, but a little too narrow for Capacitive buttons compared to other models.
On top of this, it has the front speaker which will also take up significant space.

Like I said before, the SONY Z3 is close but still has a substantial lip. If it was smaller, it would've been the perfect device.

So going back to my original point;
On-screen buttons > Hardware buttons > Capacitive buttons

Hardware buttons are better than Capacitive ones because its easier to press and gives that satisfying tactile feedback. And they can have fingerprint sensor built into it.
And On-Screen buttons are even better because they are DYNAMIC. They move away when not needed, which results in a larger screen and smaller device. Its also a simpler from a design point of view. And if you're unhappy with some aspect of the buttons, you could modify it to your personal improvement. Downsides? It lacks the tactile feedback of physical buttons, which is a fair trade-off considering what you get in return.