I was only able to pick my most common choice - Cheerios, however, I have as many as in Jerry Seinfeld's cupboard.
I don't like the sugary ones but I do like those Maple - Almond ones (can't recall the name).
Most notable are, Kashi brands, Shreddies, Shredded Wheat, Fiber1, Vector, Nature's Brand, Raisan Bran, Weetabix, and then some of the traditional ones, Corn Flakes, Rice Crispies, Special K (original), to name a few (no, I don't have every one of these in stock at the same time).