The phrase "most out of it" can refer to making the best possible use of something or to be completely clueless or unaware. There are several synonyms that can be used in different contexts. For making the most use of something, words like "optimized," "maximized," or "utilized to the fullest" can be used. When referring to being clueless, synonyms like "lost," "confused," or "dazed" can be used. Additionally, "unaware," "unconscious," or "ignorant" might be helpful in conveying that someone is completely out of touch with their surroundings. The right synonym depends on the context and nuances needed in the sentence.