Option: Zeppelin
The zeppelin
One of the options of a package delivery system is to take it to the sky and using a zeppelin to do so. While this option seems outdated it has some advantages that other technologies still not have overcome.
For instance, safety. When a zeppelin is struck by something and the gas flows out of the balloon, it drifts towards the ground on a slow manner. In comparison with a heavy helicopter or plane this is a great advantage.
Next, the lift force. A zeppelin can easily be adjusted to have a high lift force. The addition of light gasses make it possible to take heavy objects to the sky. This is a big difference with other aerial options.
Also the power consummation is much lower on a zeppelin, the balloon requires no to low additional energy, the balloon floats around. The only consummation of power is the way it propels itself through the sky using, for instance, propellers.
However, the zeppelin is a slow option. Also it is big, much bigger than a drone flying around the city. That could form a problem when dealing with urban areas.