When looking for synonyms for the phrase "most keeping," a few options come to mind. One possible substitution is "most apt," which implies a high degree of appropriateness or suitability. Another choice is "most relevant," which serves as an indication of connection or correspondence. Similarly, "most applicable" suggests practicality and usefulness. "Most fitting" is another alternative that conveys a sense of harmony and compatibility. Finally, "most in line with," indicating a shared direction or goal, is a suitable synonym for those looking to convey a sense of alignment and understanding. These synonyms should help clarify and enhance your writing.