I suggest nylon. You will have prop strikes often when learning to land. This is normal.
A wooden prop will break every time.
It won't hurt the engine. Even a Nylon prop is weaker than any metal engine part. Also most prop strikes will happen when landing and you will be at a low idle when it happens.
That said. We do have some ruts and holes in our club field that get hit on occasion. I have seen a number of planes suffer prop strikes at higher to full throttle. It always results in the engine being killed. I have never seen an engine damaged from a prop strike.