The cereal I remember liking best in my boyhood was oatmeal...and not the "instant" kind either. It took mom more than a minute or two to make and when she made it, she made a lot so we had leftovers. To me, it was even better the second day when we poured milk over a cold lump of it with enough sugar on it to send Sarah Lee into a diabetic coma. We'd then spend the next several minutes chopping and mushing it to mix it with the milk.
Of course, I went through a lot of box cereals as a kid...and later. There were the classics like Frosted Flakes, Corn Flakes, Rice Krispies, Special K, and Raisin Bran (one of my favorites)...that I still enjoy today. I also liked Sugar Pops, Sugar Smacks, Honey Combs, Captain Crunch (with or without Crunchberries), Lucky Charms, Apple Jacks, and Fruit Loops.
My all-time favorite, though, has to be Shredded Wheat. I don't buy the big old bales of it that I remember breaking apart years ago. Do they even still make it that way? Dunno. Today, I stick with the bite-size pieces...both frosted and unfrosted.