Aside from ease of generation, a major advantage of AC is that it permits the use of transformers to change the voltage. A transformer won't work on DC.
This is the reason why AC can normally be transmitted with lower losses. AC can be run through a transformer and converted to a very high voltage for transmission, then converted back to a usable voltage near the load. Transmission at higher voltage means transmission at lower current; lower current means less loss to resistance.
At a given voltage, however, AC has greater transmission loss than DC. I think this has something to do with capacitance, and perhaps some other factors. Some long distance transmission lines are now DC, to minimize losses. But this requires AC to be stepped up to the transmission voltage and converted to DC, then converted back to AC and stepped down at the end of the run. This creates a need for expensive equipment and causes its own losses, so it only makes sense for long cross-country or underwater transmission lines.
None of this has anything to do with aircraft. But I have read that aircraft AC systems are 400 HZ rather than 50 or 60 because the higher frequency makes transformers more efficient. More efficient transformers can be built smaller and lighter without causing excessive losses.