Alternating current (AC) is preferred over direct current (DC) for its efficiency in generating and distributing high levels of power. AC can easily be transformed to different voltages, making it ideal for long-distance power transmission. The oscillation of electrons in AC allows for the use of transformers, which optimize voltage and current levels for better efficiency. In contrast, DC is primarily used for powering electronic devices, as it provides a steady flow of electricity. Overall, AC's advantages in power distribution and transformation make it the dominant choice for electrical systems.