The best avocado knife is not just the most efficient tool to cut an avocado, but also a safe option for your foods. Furthermore, you do not want a knife that will stop working after a few weeks or months. From this point of view, there are a few materials to look for.
The plastic part can go in two directions. You can have hard and sturdy plastic, which is usually BPA free and safe for your foods. Second, you could have silicone, which carries the same characteristics. As for the metallic parts, stainless steel is the most common option. It will resist rust and corrosion, but it will also maintain its sharpness over time.