Some of the below points have been mentioned already. Below is a systematic method to categorize factors that will affect torque roll rate:

Input to torque roll: prop mass, prop drag

Plane's resistance to torque roll:
1) inertia resistance: plane's mass, how close is CG to the thrustline, gravity's effect on non-vertical torque roll
2) drag resistance: wing location, wing span, wing area, wing shape

*Make the thrustline as close to center as possible.
*Make the wing as close to center as possible.
*Concentrate the plane's mass close to the centerline.
*Light airframe, as the prop's counter torque has less aircraft inertia to rotate
*Small wing, preferably short wingspan: the wider the wingspan, the more it will resist torque roll. For this reason, biplane torque rolls faster than similarly loaded & powered monoplane.
*Highly tapered wing, like the Edge. For the same reason as above, only in this case the wingtip's wing area is reduced to help roll (flying roll as well as torque roll)
*Pure vertical attitude. Deviation from verticality will cause gravity to work against the torque roll.

I hope this captures every contributing factor to this system concerning torque roll. I did everything short of drawing out the free body diagram.