I agree those will be close to the final answer, but they shouldn't be. Personally I think Vaughn, but only if he could bring a top pitcher, makes the most sense to deal for a front line guy. Why?
#1, the offense is already loaded, and will be for years.
#2, Vaughn is a 1B/DH type, despite the hype that he is trying out different positions, meaning he is the easiest to replace of the position players, plus we already have depth in those spots, especially if we bring back a James McCann.
#3, We are way likely to need pitching depth over the next half decade than 1B/DH depth. Pitchers get hurt more often, they flame out more often, and have inexplicable periods of mediocrity. Even if we have pitching depth, it might not last.