Most of the electric gurus claim that any prop with a diameter/pitch ratio of less than .5 is best used for stirring paint. There are two losses in props, one is slip, the other is form drag which is the wind resistance of the blades at a zero thrust advance ratio. The fact that large diameter flat pitch props brake so well when allowed to freewheel with the motor off is a good indication of just how much air resistance the blades encounter. A smaller diameter higher pitch prop will slip more but the reduced blade drag resulting from the lowered blade tip speeds more than offsets that loss.
On an electric, you can get good overall propulsion efficiency with a "climbing prop" by using the prop to climb and then shutting the motor off and gliding for a while and repeat. Make sure the motor brakes the prop and doesn't let it windmill.

A 3-D plane hovering on prop thrust is another matter entirely. Here, all props have an efficiency of zero because they are doing zero work. It's a matter of which prop consumes the least power.