1. Madara Uchiha for sure, he fought the 5 Kage's, each one of different calibur and skills. They couldnt penetrate his Susanoo. Also a full 360 defense.
2. Gaara, he is completely anti-amaterasu, his sand can block every corner of incoming attack, also if he was Jinchuuriki with Shukaku he be even more powerful in defense. His defense is full 360 which makes it better.
3. Itachi Uchiha, His Yata Mirror according to Zetsu is impossible to penetrate, but this is only at one position which is a problem fighting ninja's such as Raikage or Neji, since they attack full 360.
So if you are thinking why is Itachi third? Well his defense wont act well in pressure, such as Madara vs 5 Kage's.
Or Gaara vs Sasuke at Summit along with collapsing building.
2. Gaara, he is completely anti-amaterasu, his sand can block every corner of incoming attack, also if he was Jinchuuriki with Shukaku he be even more powerful in defense. His defense is full 360 which makes it better.
3. Itachi Uchiha, His Yata Mirror according to Zetsu is impossible to penetrate, but this is only at one position which is a problem fighting ninja's such as Raikage or Neji, since they attack full 360.
So if you are thinking why is Itachi third? Well his defense wont act well in pressure, such as Madara vs 5 Kage's.
Or Gaara vs Sasuke at Summit along with collapsing building.