Carbon by all means. I assert that the preference for stainless is a marketing phenomenon. carbon steel blades from the middle ages are around, and serviceable-rust is just not that big a problem. Stainless is generally harder to sharpen, more brittle, and not amenable to forging. The stainless blades generally available are ground out of steel blamks by soul-less cnc technology in mass numbers. Using carbon steel allows each user to make his own knife out of available scrap material at lower cost and higher quality than is available in the market.