1 month ago (Pre-release)
In my experience, in the right hands, Loot Council unequivocally better for the success of the guild in regards to progression. Get the right pieces to the right people in order to achieve success. With that being said, if your leadership/council play favoritism or puts personal issues in the way, then your guild will suffer harder than a poorly run DKP system.
My vanilla guild on Malfurion started with DKP and ran into some issues early on with hoarding. People were turning down clear upgrade in favor of something else that they wanted. These upgrades were then being sharded and wasted.
A big discussion was made on our forums, we voted and scrapped the DKP system for a Loot Council system. Because of the switch, we lost a few members along the way, but in reality, those individuals weren't real team players, to begin with, and it was a positive loss.
Our guild thrived under Loot Council. Our Loot Council was extremely fair in all but 95% of the looting (we're human and make some mistakes here and there). If a close call came between two people in regards to upgrade, attendance was factored in. If that was equal, they rolled off. The arguments, the gossiping in /tell, the drama stopped. You knew exactly who was most likely getting which pieces first and you knew when you were guaranteed second, third, etc.
Overall, I think both systems work. I prefer Loot Council.