Is tethered drone lighting a thing? Seems like a thin wire with a high voltage going to eight propellers and a set of LED panels would be quite efficient and flexible.
Blimp requires far more maintenance. Rain is manageable, heavy storms and winds you just park it or lower it when needed. For urban centers, blimp moonlighting seems like a really neat feature. Could even do "digital projection" to focus light on desired areas.
Noise can be reduced because the fan blades can be larger and spin slower, does not need to be compact.