The phrase "most true-to-life" suggests something that is highly accurate and realistic. Its antonyms could include terms like "unrealistic," "exaggerated," "fantastical," or "unbelievable." These words indicate a lack of authenticity or accuracy in whatever is being described. For example, a film that is "unrealistic" may feature plot points or special effects that are clearly impossible in the real world, while an "exaggerated" story may represent characters or events in an overblown, hyperbolic manner. In contrast, a piece of writing or art that is "most true-to-life" is likely to be viewed as credible and believable.