What is the strongest metal to make a katana?

If I'm looking to craft the ultimate katana, which metal would offer the greatest strength and durability? Is there a specific alloy or blend of metals that's considered superior for such a blade? I'm particularly interested in knowing what material would provide the best edge retention and resistance to breaking or bending under stress. Could you elaborate on the pros and cons of different metals commonly used in katana making, and perhaps point me towards the strongest option available?