Final answer:
In 'Wonder', August Pullman disliked his unusual facial appearance the most, which brought him significant emotional distress and social obstacles.
Step-by-step explanation:
In the book Wonder, August Pullman, also known as Auggie, hated most about himself the way he looked due to a facial deformity. Auggie's physical appearance caused him a great deal of emotional pain and social challenges, particularly as he ventured into a mainstream school for the first time. His struggle with self-acceptance and the reactions of others to his face are central themes in the novel.