I don't have the answer BossBabaPanda, but I am also curious and would like to contribute to the precision of the question. I assume that the discipline bonus is additive, and that the 15% for each point of extra (soj & manald) discipline is a percentage increase relative only to the base damage, not relative to the damage as already modified by the discipline you had before equipping the rings. Furthermore, that the focus & restraint buffs are multiplicative with -both- the damage from discipline (ofc w/o manald&soj) and with each other (given 100 dps, 2x50% is not 200 dps but 225, etc).
In short, more discipline is more of the same, while focus and restraint is threefold multiplication. My intuition tells me F&R will be better, but I can't check since I'm at work and can only play by forum proxy.
Edit: It seems Kuristina beat me to it and provided a convincing answer. +1