Why? Because, other then being a power house, he is a loyal shinobi who i ahs the will power to resist having his mind read and is willing to sacrifice his own life for a goal. To protect intel. He has had a pretty bad life and is confused on his stance in the shinobi world, but unlike most characters he isn't redeemed and ends up having a lonely death. He is a slightly tragic character with an awesome attitude.
Also, Orochimaru. Because why the Hell wouldn't you?