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.