The antonyms for the phrase "most unprepossessing" are words that describe something attractive, appealing, or beautiful. Some of the antonyms for this phrase include gorgeous, stunning, glamorous, impressive, attractive, lovely, charming, enchanting, appealing, and delightful. These words indicate a positive and favorable appearance or impression that a thing or a person can create. They are mostly used to describe people, places, or objects that capture the attention of their audience because of their exceptional qualities. While the phrase "most unprepossessing" emphasizes a negative connotation, the antonyms provide positive and optimistic adjectives to counteract it.