Like creatine, arginine bonded to any of the Krebs Cycle intermediate such as citrate, fumarate, malate, succinate, and alpha ketoglutarate, or compounds involved indirectly in the energy cycle, for instance, orotate, pyruvate, and so on, yields improved absorption, bioavailability, and potency.
Consequently, I would prefer arginine alpha ketoglutarate. You will get all the endothelial-lining-support and vasoldilation properties of arginine plus a number of cool benefits of alpha ketoglutarate (AKG), such as more arginine stability, bioavailability and absorption. Furthermore, alpha ketoglutarate will serve as a transport medium for arginine, making it directly available at the cellular levels for optimal synthesis. Beyond this, alpha ketoglutarate improves the endogenous production of of glutamine and glutamic acid, both important for muscle growth and for the immune system. AKG also binds to toxic ammonia in muscle cells, in the liver, and in the brain, thereby converting ammonia into glutamic acid, improving glutamine levels and assisting in elimination of toxic ammonia from the body. Lastly, as a Krebs Cycle intermediate, AKG improves VO2 Max and energy metabolism in muscle cells, and is consequently a potent ergogenic.
Arginine alpha ketoglutarate all the way!