Determining the "highest quality" steel depends on the specific application and the desired characteristics. Different steels excel in various areas, such as strength, hardness, corrosion resistance, or heat resistance. Here are a few examples of high-quality steels known for their exceptional properties in different contexts:

1. Tool Steel: Tool steels, such as D2, M2, or S7, are renowned for their exceptional hardness, wear resistance, and toughness, making them suitable for cutting tools, dies, and molds.
2. Stainless Steel: Stainless steels like 316 or 440C offer excellent corrosion resistance, making them ideal for applications in harsh or corrosive environments, such as marine or food processing industries.
3. High-Speed Steel: High-speed steels, such as M42 or M35, are known for their exceptional heat resistance and ability to maintain hardness even at high temperatures, making them suitable for cutting tools that operate at high speeds.
4. Carbon Steel: High-carbon steels, such as 1095 or W2, offer excellent hardness, strength, and edge retention, making them popular for blades, knives, and swords.
5. Tool and Die Steel: Steels like A2, D3, or H13 are commonly used for tool and die applications due to their combination of hardness, toughness, and wear resistance.

It's important to note that the "highest quality" steel for a specific application also depends on factors such as the intended use, budget, and manufacturing requirements. Different steels have specific advantages and disadvantages, and the selection should be based on a careful consideration of the desired properties and the demands of the application. Consulting with experts or professionals in the field can provide further guidance in selecting the most appropriate steel for a specific purpose.