Antonyms for "most unentertaining" would be words or phrases that describe something that is enjoyable, engaging, entertaining, or amusing. Some antonyms for "most unentertaining" could be "engaging," "enthralling," "fascinating," "riveting," "stimulating," "exciting," "thrilling," "entertaining," "captivating," "enjoyable," "magnetic," "interesting," "amusing," "charming," "delightful," "inspiring," "pleasurable," or "captivating." These words could be used to describe a variety of activities, such as movies, concerts, books, sports events, games, parties, or social gatherings.