The phrase "most hot-and-cold" implies inconsistency, indecisiveness, and wavering. Its antonyms are words such as unwavering, resolute, steady, constant, and consistent. These words suggest a firmness of purpose or character that is opposite to being hot-and-cold. They connote someone who is dependable, predictable, and trustworthy, as opposed to someone who is fickle or ambiguous. In contexts where stability and persistence are valued, these antonyms are highly regarded. They speak to a person's reliability, integrity, and perseverance, traits that are often admired and respected in personal and professional relationships.