I don't eat cold cereal very often. When I do, I like the flavored Kashi cereals (not the original. . .it tastes like brown paper towels

). The blueberry one, the one with freeze-dried strawberries, and Berry Blast (I think that's the name), which tastes like Cap'n Crunchberries, but without all the nasty ingredients. I cut high-fructose corn syrup out of my diet a few years ago, and that eliminates most cold cereals, unfortunately.
For hot cereals, I like oatmeal mixed with multi-grain hot cereal mix (Bob's Red Mill brand, I forget exactly what's in it). If I don't have time for making the good stuff, I'll use an instant with no artificial colors or HFCS. Oat Revolution is a good one.