Prop selections depends mostly on your model, flying style and expectations. Changing props is like driving a standard shift in different gears. First gear gives snappy acceleration and fast response but low top-end speed. Third gear is poor acceleration but faster top-end. Props offer the same choices. You'll never make a Lazy Bee a racer no matter the prop and you'll never 3-D a Quickie 500, but there is a best prop for each for any pilot. Experiment.