The Backbone Pro Xbox Edition looks like an improvement over the pre-existing One controller in nearly every way. It's still a USB-C shell that wraps around a phone or related device, but the actual controller is now more in league with an actual Xbox gamepad. It features full-size control sticks, hall effect triggers and two customizable back buttons. Most of the inputs can be remapped.
The Xbox Elite Series 2 controller has a heftier feel, made from heavier materials to give you some real weight to hold onto in your hand when compared to the standard Xbox wireless controller. It's also got a rubberized grip and short hair triggers. The thumbstick mobility can be adjusted to your exact preferences, plus you get a lot of swappable parts to truly cater to your playstyle.