Steel can be categorised into these four types: Carbon, Alloy, Stainless, and Tool.

Mild steel is lesser in impact resistance when compared with stainless steel. On the other hand, stainless steel is less malleable than mild steel. So mild steel is good for fabrication while stainless steel is used for cutting tools. Hence, both are better for specific purposes related to their properties.

 Alloy steel contains other elements, such as chromium, nickel, or molybdenum, in addition to carbon. Carbon steel, on the other hand, contains only carbon and small amounts of other elements. Alloy steel is typically stronger and more durable than carbon steel.

Cast iron contains high levels of carbon, typically between 2% and 4%. Steel, on the other hand, contains lower levels of carbon, typically less than 2%. Cast iron is typically more brittle than steel, but it is also more wear-resistant and can be cast into complex shapes more easily.

Various types of steel are resistant to corrosion or rust but stainless steel contains the element chromium, which is highly corrosion-resistant. Hence, stainless steel is the answer.