Is it better to eat raisin bran cereal that is Pas Yisroel, than to eat another brand of the same cereal that is not?
Grain products need "tzuras hapas" to qualify for the takanah of pas yisrael
Cereal doesn't have "tzuras hapas" - it doesn't look like a baked food (like bread, pretzels, or bagels.)
The Source of the above quote also quotes Rashi on Menachot 75b
So, it's actually impossible to have a "Pas Yisrael" raisin bran, since bran flakes don't qualify for the takanah in the first place.
Acc to the Ramma in yo'd siman 112 siff 6 kichel are included in the category of pas as far as pas yisroel goes. The shach in s.k. 18 points out that that is only true if they are made drom a thick dough and have tzuras hapas, the chochmas adam explains that if they are made from a thin dough they fall under the domain of bishul akum which is actually more stringent, i.e. there is no heter of pas palter.
This is an explicit example, but its a general law that if the law of pas doesn't apply, then the law of bishul does. So either it needs to be pas yistoel as a chumra, or bishul yisroel as ikur din. Depending on what the mixure was like raw. Of course whether or not cereal is oleh al shulch milachim would weigh in to possibly exempt this food from all regulations.