Actually, if you look at the nutritional information on Kashi's products, they're often not the best. I love their Heart-to-Heart, but I've stopped eating it because it's much higher in carbs than others.
Kix is a great one, and Cheerios has expanded their flavor selections so much in recent years. I personally love the Chocolate ones.
Chex are always good, but it's often a personal preference between rice, corn, wheat, etc.
Granola is often really high carb as are Grape Nuts and meusli.
One thing you'll really want to look for are serving sizes and then nutritional information (calories, fat, sodium, carbs, in particular). Rice Krispies allows you a much larger portion than Frosted Flakes, for example.
We let our kids have Frosted Mini Wheats on occasion, but they're really good about eating things like Special K (if you can believe it).
I hope that helps. Most of my information is based upon 8 years in the world of Diabetes and working with dieticians (as well as a mother with type 2 diabetes and trying to teach her nutritional information as well).