I have only ever burned Royal Oak in my Kamado Joe, because I can get it year round, and it is pretty affordable. 17.6 pounds for 11.00 (.625/lb). I usually buy about 5-6 bags at a time. I nearly always find 1-2 rocks, or 1-2 pcs of insulation in the bags. My theory on smaller unusable pcs in the bag is due to retail handling. I figure the majority of it is stocked by younger minimum wage high school students. I dont expect them to be gentle, and the bags dont say "fragile" anywhere.
I am not sure there is a perfect charcoal out there, and everyone has an opinion. I do like the way Royal Oak performs, but to be fair, I havent compared it to anything else when it comes to cooking.