Both manual and auto-ignition are equally efficient. For using the auto-ignition mode, you just need to turn the knob in a particular position. Hence, you don't need a lighted matchstick or a gas lighter in putting it on, unlike the manual mode. This makes the auto-ignition mode convenient. However, you need to replace the batteries at frequent intervals, since auto-ignition runs on batteries. If you don't replace the batteries, then you'll have to switch to the manual mode.