It's not entirely clear what George specifically likes in the book "Marvellous Medicine" by Roald Dahl. We know he loves his Grandma, even if she is incredibly grumpy and mean to him. He enjoys reading about inventions, and he's curious and enjoys trying new things. However, there isn't a specific object, activity, or person that he's explicitly shown to love or prefer.
It's more about what he doesn't like:
* He dislikes his Grandma's meanness and the way she treats him.
* He finds his life boring and monotonous.
* He doesn't like being constantly lectured and told what to do.
So, while we don't know what George likes, we know what he dislikes, which motivates him to invent his "marvellous medicine" and change his life.