Jiraiya, He has a sense of goal and purpose to what he wants to bring to the world; I understand he may not always be there based upon his books, or his much needed adoration with the ladies; But his grasp for what needed to be done was always there. Unflinching love for anyone he cared for, open minded, hilarious!! I particularly found him to be an amazing and patient teacher I mean He taught and trained and molded naruto into who he was, lets look how he started? A brat who couldn't do anything or think clearly. Anyone who can train naruto into a level headed un predictable machine is dead set the right choice for a teacher!
Needlesss to say easy to be bias when he's your favorite character.