I rarely ever buy full-price name brand cereal anymore. $4-$6 a box is just ridiculous! Between Meijers, Kroger and Farmer Jack its pretty easy to find a good sale on cereal just about any week of the year.
For MSB, these are the Kroger off brands I have tried:
Cocoa Puffs - Awesome, almost as good as the General Mills
Corn Flakes - OK, but kinda bland
Raisin Bran - Good
Fruit Loops - Good
Cinnamon Toast Crunch - Very good
Fruity Pebbles - Good
Frosted Mini Wheats - Awesome
Honey Comb - Awesome, my favorite
Cheerios - Very good
Apple Jacks - Very good
I know that there is 1 or 2 of them that I didn't like. None are coming to mind though. For the most part, they are all good or at least tolerable.