CC BEC is better because it is smaller, cheaper, and far more powerful

BEC - Battery Eliminator Circuit is a device that eliminates the need for a receiver and servo battery pack. It draws higher voltage from the motor batteries and drops it to a voltage level that is suitable for your receiver and servos. This is required in applications which draw high power for multiple servos or use more than 3S motor packs, as most ESCs with linear BECs are not designed for these applications.