The antonyms for the phrase "most unpretending" can vary depending on the context in which it is used. However, some possible antonyms include "ostentatious," "pretentious," "showy," "flashy," and "affected." These terms suggest a lack of authenticity and an exaggeration of one's qualities or possessions, which is the opposite of being unassuming, modest, and humble. Other antonyms could be "conceited," "arrogant," "haughty," "snobbish," and "self-important," indicating a vain and superior attitude that lacks sincerity and respect for others. Thus, by contrasting with these negative qualities, being "most unpretending" implies a positive character trait that embodies simplicity, honesty, and genuine humility.