I agree with Kramer, it is general knowledge that given the same engine RPM, 2 blade props are more efficient and that's why racers sometime have one blade props.

The only difference is in the ground clearance. For the 2 blade props, the diameter is higher and thus the ground clearance required is higher. 3-4-5 blade props all allow more ground clearance while still allowing the engine to operate at optimum RPM.

Thus, for beginners, 3 blade prop is fine as long as it's not that much more expensive. Just imagine how much more prop you would be grinding off after each landing if the prop was half inch-one inch longer :-)