The term "most cast-off" refers to something that is disregarded or abandoned, and it has various antonyms depending on the context. If the object being discussed is of high value or importance, then the antonyms could be treasured, coveted, or prized. Conversely, if the context is about a person's status or popularity, the antonyms could be esteemed, admired, or revered. In terms of fashion, the antonyms could be fashionable, stylish, or trendy. When it comes to durability, the antonyms could be sturdy, resilient, or enduring. Therefore, the antonyms to "most cast-off" vary depending on the concept being discussed.