I would argue that the smoother the surface the kinder it is on the rope, but I think that is probably just semantics as harder materials usually maintain a polish better.
Cast alloy is often full of manganese to make for easier casting, but it corrodes easily, which is why people talk about billet being better.
Again semantics, but if you cast a block of metal you would usually call it an ingot, it becomes a billet once it's rolled / forged to size. The rolling / forging should increase the hardness and create a more uniform crystal structure in the metal.
Based on the above, the bee's knees material would be polished forged stainless knife steel. But that might be a bit of an overkill.
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