John Kerry. The only person who could, by comparison, make Hillary Clinton look better as Secretary of State.
Private citizen (even though a very public figure, still a private citizen) making comments in a private setting versus somebody officially representing the USA making comments officially and publicly in an international forum. Kerry, no contest.
Between those two I pick the traitor.
Kerry.
John Kerry speaks for the United States, when he speaks, he makes fools of the whole country. When Sterling speaks, he is only speaking for himself.