I'd give it to both, but Law fulfilled his life's purpose in Dressrosa; after that, he's been holding onto a plot that's just his curiosity, not much ambition in it. Sabo, on the other hand, carries Ace's will; his influence surpasses even Dragon's, and Sabo has the desire to change this world, which has the characteristics of a King here...
But screw it, I'd give it to both, just not to the admirals, who are slaves.