Getting Van Persie would be a much greater improvement in quality for Man Utd because he would be replacing Welbeck and partner with Rooney; whereas in Man City, for Van Persie to play some other quality player will have to be benched. By that reasoning, for the same price, Arsenal should take Man City's bid. Also Arsenal will try to get the money for a new striker from the Van Persie sale which is where Juve might fall short.