Someone pointed this out on Twitter that I think was interesting and going with the poll, answers why Sanji will be last of the trio to awaken CoC.
All three of the trio started out as failures. Luffy was losing to Ace and Sabo his childhood, Zoro to Kuina, and Sanji to his siblings. But where Ace and Sabo picked Luffy back up and supported him, and Kuina and Zoro pushed each other, Sanji gets thrown in a cell and called worthless.
All three started out as failures that become kings, but only two had support.