I have not seen them in a long time, but when I used to backpack and climb, there was a sock called, I think, the Norwegian RagSock? They were expensive and usually were only found in top-notch outdoor/camping shops. They were made from a very dense pure wool fibre, that had super wicking properties. The toe and heel areas were reinforced to prevent 'slippage' by the foot so as to minimise blisters being formed. All in all a great sock, one of the best I ever saw.

In the absence of that, any natural fibre is surely better than anything manufactured?