The phrase "most low-down" is often used to describe something that is deceitful or dishonorable. If you were looking for antonyms for this phrase, you might consider words such as honorable, respectable, or ethical. Other possible antonyms could include trustworthy, truthful, or forthright. In general, antonyms for "most low-down" would be words that imply honesty, integrity, and uprightness. By choosing antonyms that reflect positive values, you can help to counteract the negative connotations of the original phrase and promote a more positive mindset.