I'd go with a drone. It's more cost-effective, and they can be flown almost anywhere. On the other hand, filming while riding in a hot air balloon might give you more control, since you'll be physically manning the camera. Still, I'd pick the drone.
Hot air balloons could be risky depending on the location, so I'll always opt to use drones. Although both require experience, drones would be much less hassle because of their size. You only have to be careful controlling it since they are expensive.