[cashflyer]

My guess is Felix Gaeta.
Partly, because he is now singing to music in his head.

But mostly:
For the three years prior to the Cylon attack on the Twelve Colonies, he served as William Adama's Senior Officer of the Watch aboard Galactica. He was in a position to influence decisions, such as staffing decisions that allowed the 4 of the final 5 known to us to be onboard Galactica.

Adama to relies heavily on him as a member of Galactica's command crew - adding to his ability to influence.

As Tactical Officer, Gaeta manages the ship's FTL systems - perhaps explaining how the Cylons keep finding them.