The phrase "most atop" can be replaced with a variety of synonyms depending on the context of the sentence. For example, "most at the top" can be replaced with "highest," "uppermost," or "peak." Similarly, "most atop" can be substituted with "on top," "at the summit," or "upward." If the sentence refers to something being the most prominent or visible, "most atop" can be replaced with "most visible," "most noticeable," or "most apparent." In any case, it is important to consider the context of the sentence and choose a synonym that conveys the same meaning while fitting the overall tone and style of the writing.