My vote goes to zazu. Why?
He's extremely loyal to the royal family. Even after being teased by the cubs, smashed by a rhino, and faced with three hungry predators all he can think about is simba and nalas safety.
When simba is facing a herd of charging wildebeasts, zazu is frantically searching for him. Before scar knocks him unconscious, his first line of thought is to find others for help.
When simba is ascending to throne, he has a look of awe that is both a sign of respect and acceptance.
I also love rowen atkinsons performance. If you've ever seen blackadder or mr bean you know that he's a fantastic actor and has a lot of range