Half of the people here likely never even read the OP and went off to what seems like a whole different thread. GRAPE NUTS vs. CHEERIOS is what the OP is asking about and (my guess) probably not looking for a doctoral dissertation. Just some simple answers and why.
I eat both. I know the carb load on cereals in general are substantial but keeping the sugar grams down compared to the total carb grams is what I try to do. For a pure health standpoint I have no idea which is better. Unless you're a top athlete I don't think it should matter vastly which of the two you choose. Do your "research" here and on the net then just go with what suits you.
For instance if you take Cap'n Crunch, Grape Nuts and Cheerios you don't even need to read the box to know which one not to eat. I actually mix Grape nuts with Cheerios to get some crunch and some texture to otherwise bland cheerios.
Prince EXO3 Tour 18x20, 12.5oz, 9HL, Tonic 66/62, S&V, D2 '88-90