I try to keep P's breakfasts wide and varied so that she is not the type of kid who eats the same cereal day in and day out.
When P was first weaning, she would always have some sort of fruit puree for breakfast. Being obsessive compulsive, I would ensure that she wouldn't have the same puree more than once a week. Fruit purees are often the easiest to do I've found, as many are soft and don't need steamed/boiled beforehand. A lot of fruits cannot be cut/peeled prior to the meal either, thus neccessitating immediate preparation.
After she was a bit more confident with textures and chewing, we introduced crushed organic Weetabix with mashed banana, which P has a few times a week for breakfast now. I don't always just add banana, but any other fresh fruits I have to hand. I should think that there are quite a few other low-sugar cereals that are similar if you can't get Weetabix, for instance, Shredded Wheat.
We are also lucky enough to have a new product available here called My First Muesli, by Cow and Gate. It's a muesli (go figure) with just enough texture, plus it has no added sugar or salt. I remember looking for low-sugar muesli for myself a couple of years ago, and I was appalled at how much sugar content most of them had! I'm glad that P can gain all the nutrients that muesli provides without all the sugar. For flavour I add fresh fruit to this too. For extra calcium, some plain Greek yoghurt.
Another handy breakfast food, especially as we are entering the winter months, is porridge, or as Americans would say, oatmeal. I buy a really cheap pack of porridge oats, just add milk, heat it up, and then add either fresh fruit, or fruit puree. Depending on the fruit, I sometimes add a little cinnamon as well. P loves it, and it seems like such a lovely, cosy meal to start a cold day.
If the oatmeal is too textured, just whiz it in the food processor/blender to achieve the required consistency.
Are there any specific breakfasts your babies/toddlers adore?