Pheadra I.
One with enough proteine, carbs and fibres. So I'd say fruit, like banana. Next to that it's a good idea to switch between an egg and oatmeal every day, since repeated usage of both isn't healthy but switching it up is! Also, I'd recommend drinking milk next to your breakfast. Weither it's actual milk or a vegan variant like soy drink is up to what you like most. I like soy drink most because of it's natural sweetness without added sugar and the lower percentage of fat.
