According to Mrbreakfast.com the top 5 Cereals, Including cereals that have been discontinued are:
1. Quisp (WTF IS THIS?!?!?!)
2. Frosted Flakes
3. Cinnamon Toast Crunch
4. Honey Nut Cheerios
5. Cap’n Crunch
Personally, i’d have Reese’s Puffs up there, as well as Waffle Crisp... but both of those land at #64 and #32