At that particular point time bothTsunade and Danzo had a different way of thinking.Danzo step was out of practicality,he knew nothing about naruto and thought calling him would be just handing over the 9 tails to Akatsuki without any effort.Whereas tsunade's step was more bcoz of her faith and belive on Naruto,his will and his abilities which was an offcourse a better step bcoz danzo never thought pain would easily captured the jinchuriki after the invason outside konoha.just he had to do is to find out his location ast some point or the another there has to be a face off between the two....