Avoid the grey Cox props. The ones to get are the black plastic Cox props.

I've found that both APC and Master Airscrew props are of medium brittleness due to their use of glass fiber filled nylon. So neither of them take a lot of punishment before they break.

If you can find any of the Grish/Tornado white nylon props in the sizes you want they are very crash resistant as well.

One point about either the black Cox or white Tornado nylon props. They will be more flexible and crash resistant if you boil them in water for about a hour. It doesn't need to be a hard rolling boil. Just bring it up to a bubble and turn it down to medium-low with a cover on the pot so that there's a slight but constant bubbling going on. Check a few times to make sure the pot doesn't boil dry or you'll be the week's Home Hero for sure...