A five-blade fan is typically more effective than a three-blade version because it can better circulate air in the room, reducing temperature fluctuations. However, an eight-bladed model will do even better due to its increased surface area that can use wind currents from different directions. If you're looking for something less powerful but still want to have some circulation, then three blades should be fine as long as your ceilings aren't too high above ground level (over 12 feet) since they may not reach far enough up there with their limited airflow potentials.