Vidal>Higuain. By miles. He not only has a harder task on the pitch, and in a tougher league, he also does his work more consistently.
I remember asking all of us this question not too long ago. It was inevitable for clubs to sit up and take notice of this player. He is soon going to be the best in the world in his position, and it was good to see the club value him like most of us did, and replied to that question I raised. Vidal isn't going anywhere for the next decade as far as I'm concerned.