Neither is objectively better, it just depends on whether you value stainless convenience or a laser-sharp carbon edge. Go with SG2 if you want a knife that holds a screaming edge without any babysitting. Choose AS if you are chasing the thinnest possible edge and don't mind wiping the blade down after every use.
SG2 is a powdered stainless steel from Takefu, usually sitting around 62-64 HRC. It is tough and resists corrosion, which is why I reach for it when working with acidic foods. Aogami Super is high carbon and typically harder at 64-66 HRC. It sharpens to a hair-whittling edge that lasts slightly longer than SG2, but it will rust if you neglect it.