I have used Animal M Stak before and thought it was a good product. I felt fuller, endurance was better, and i added some reps to almost every exercise. Nothing crazy but for a natty product i definately enjoyed it. My mood also seemed to be better during the time of usage. Also the nutrient partitioning was a nice effect that i wasnt expecting, i ate more, stored less fat, and looked fuller.
Next on the list is Animal Flex, or Animal Test. Love me some AA!