I prefer oil filled heaters and here's why.....
I agree that an oil-filled heater is still around 1500-watts, but when the oil is hot the thermostat will turn the element off and the heater will keep on heating (with the element off) for a long time. It's kinda like a car coasting down a long hill and using very little gas.
The time between off and on cycles is way longer than my plain ole electric heater, and that's saving me money. Turn the heater off or unplug it and it will keep heating until the oil completely cools down to room temperature.