Probably China have greatest BTC adoption potential - China have population ~ 1.381 billion. Argentina's population is ~ 43 millions only. So in China potential is quite larger.
Logically we will believe that china have bg potential in bitcoin adoption because their population so big,and biggest in this world,but also we should know that china also have poor people there,and its still hard for them to using bitcoin,and argentina look like better from wealthy factor.