My T2 deck's worst nightmare is Isaiahmaiahha.
Not sure why, didn't you use my defense at one point
That eats Isaiah alive.
Isaiah is incredibly powerful, as are decks that take proper advantage of him. Call alone negating the important stuff is terrifying, and he has CBN battle-winners. The problem with the latter, though, is that he gets bad initiative (especially banded with angels), and none of the Isaiah enhancements negate a just-played evil enhancement and simultaneously win the battle.
King David is beastly and I PBI is nasty in general (though his is not as targeted as others).
All things put together, I go with...King David. Though it is close.