When it comes to antonyms for the phrase "most eye-opening," there are several options to consider. Some possibilities include "least surprising," "unrevealing," "ordinary," "mundane," "predictable," and "boring." These terms imply a lack of novelty or new insights, rather than the enlightening, awakening feeling of something being truly eye-opening. However, it is important to note that what may be mundane or predictable for one person may not be for another, and that personal experiences and perspectives play a role in what is considered truly enlightening. Therefore, it is up to each individual to determine what they consider to be most eye-opening or its antonyms.