It totally depends on how lazy I am feeling at the moment. 
I always have boxed cereal and milk available on those days when I’m feeling really lazy and just want something to eat quickly. When I have a bit more time, the slightly less lazy route, but still carb-heavy, is oatmeal with hopefully some sort of granola or muesli on top and whatever fresh berries are in the fridge.
When I’m feeling fancy, though, my go-to is a French-style omelette: light, fluffy, and creamy all at the same time. I go the simple route – a little cheese, maybe some grilled onions and/or mushrooms, and topped with parsley or green onion.
If I’m heading out for breakfast, then I’m a diner junkie. I’ll eat anything on the menu because it all makes me happy. 
We also have a French-Asian fusion patisserie nearby… That stuff is fantastic! (Tous les jours – If you have one nearby and haven’t stopped in, then you definitely should visit!)
Above all that, though, you really can’t beat a good brunch buffet. Why choose when you can try everything!