We can give you a quick answer, because it’s no contest: fans. Whether you’re talking about using just the blower fan of your HVAC system (“fan only mode”) or ceiling fans, these devices use only a small fraction of the amount of energy of turning on the air conditioner.
For example, a standard central air conditioner, like the one you probably have in your house, consumes between 3,000 and 3,500 watts of electricity per hour. That same AC when only the fan is running consumes 500 watts of electricity per hour. That’s an enormous difference! Ceiling fans use around the same amount, 500–750 watts per hour.