If he had lived, maybe Goldwater himself? Don't know how friendly he was with McCain but surely would not like Palin.
I don't think his distaste for Palin would prevent him from voting for McCain - a fellow maverick Republican and his successor for the Arizona senate seat - and it most certainly wouldn't compel him to go as far as to vote for Obama.
Although in its way it would be ironic for Goldwater to vote for an African-American presidential candidate, given his own legacy with African-American voters.