On a personal thought, I'll say Boo, because he is my favorite character since I played with him in Mario Party 7. (No, I do not have other games that Boo was before Mario Party 7 ...) However, I would have also liked to have Dry Bones and Hammer Bro.. I can also say Blooper. (But not as much as the ones I have mentionned before.) This is what I think ...