AC is more efficient for distribution because it is easy to step up/step down the voltage levels using a transformer. However, for very long power transmission lines, at very high voltages like Hysteresis loss, skin effect , capacitive couplings resulting in charging/discharging leading to some more losses. DC can be done like that. Transmission is a big headache for DC. Even HVDC (High voltage DC ) is complex to transmit , it will be fruitful only for end to end transmission.