Determining the "most durable" katana is subjective and can vary based on individual preferences and the specific criteria used to evaluate durability. However, several factors can contribute to a katana's durability. Here are some considerations:

1. Blade Material: High-quality steel with appropriate hardness and flexibility contributes to a katana's durability. Traditional katanas often used a combination of hard and soft steel layers, such as the differential hardening technique, to achieve a balance of sharpness and resilience.
2. Construction Technique: The forging and heat treatment methods employed during the sword-making process can significantly impact a katana's durability. Skilled craftsmanship, including proper shaping, folding, and quenching processes, can enhance the sword's overall strength.
3. Tang Construction: The tang is the portion of the blade that extends into the handle. A full tang construction, where the tang extends the entire length of the handle, is generally considered to improve a katana's durability and strength.
4. Hilt and Fittings: The quality and materials used for the hilt, guard, and other fittings can influence a katana's durability. Solid construction and high-quality materials, such as wood or ray skin for the handle and brass or iron for the guard, can enhance its overall resilience.
5. Care and Maintenance: Proper care and maintenance, including regular cleaning, oiling, and correct storage, are crucial to preserving the durability and longevity of any katana.

It is essential to note that the durability of a katana is not solely dependent on a specific model or brand but also on the craftsmanship, materials, and care put into its creation. When selecting a katana, it is advisable to consult with experienced sword enthusiasts, reputable dealers, or professional swordsmiths who can guide you toward a high-quality and durable option.