I love Post’s Great Grains-all that nutty/fruity/crunchy goodness. I usually serve it in my yogurt however. This is despite finding half-a-bee in a box once.
My fave was Cap’n Crunch’s Vanilla Crunch (had a lady whale on the front of the box).
Now, I just eat Walmart knock-off Rice Krispies. Not bad.
I really enjoy Life cereal and the simple nothingness of either Cherrios or Corn Flakes.
Life is my current favorite, but the short-lived maple-and-brown-sugar Life was even better. I think they still theoretically make it, but if so, it’s in very few stores.
My own honey cranberry pecan granola.
Currently it’s Froot Loops. It changes.
Honey Nut Cheerios
I don’t eat much cereal but when I do it’s mostly Frosted Flakes. They’re…well, you know.
I loved Trix when I was a kid.
I can’t see those without thinking of Omar from “The Wire”.
I eat Crispix most weekday mornings. Sometimes I’ll go for Cheerios. I like to add chopped dried dates to my Cheerios. Once in a while I’ll pick up a box of Grape Nuts or Special K. But Crispix is my default.
I still like Trix, but they changed it to include odd shaped pieces along with the colored balls, and it just isn’t as good.
I’ve always loved Golden Grahams, except that they have a crisp-life of about 30 seconds in milk, so you have to put about two spoons,worth in at a time then eat and repeat.
I haven’t had it in decades, but King Vitaman was my favorite, even though it would tear the hell out of your mouth.
Also cinnamon Puffins, Cracklin’ Oat Bran, and Mini-Wheats.
Wheat Chex. Don’t particularly care for Rice or Corn Chex, but gimme the Wheat Chex.
Kashi Island Vanilla wheat biscuits. Perfect amount of sweetness for me.
For sugary it’s Cap’n Crunch all the way.
For sorta healthy it’s Basic4.
I generally alternate between Frosted Flakes and Honey Nut Cheerios.
As a kid in the 70s I ate all sorts of teeth-rotting fare, all the Cap’n Crunches, the ‘Monster’ cereals (including Fruit Brute, once, Bleeech!) Quisp and Quake, and the major Kelloggs stuff (never liked Post much).
Becoming diabetic I tend to stay away from most Adm Sugarman’s Sugar Coated Chocolate Sugar Lumps flavors these days. 
Life and Kix are ok, but mostly stuff like Wheaties, Corn Flakes, Special K with Berries, Shredded Wheat etc. Always name brands, never generic, and usually with a generous amount of Splenda of course…
Honey Smacks. They used to be called Sugar Smacks, until they reasoned that Honey Smacks sounds healthier.
Frosted spoon-sized mini-wheats, usually the store brand or generics.
Also store brand Grape-Nuts but I usually let them soak and warm them in the microwave to make a porridge.
I don’t think they make it anymore but my favorite was S’Morz.
Growing up it was Fruity Pebbles (hated Cocoa Pebbles!) or Apple Jacks.