When describing someone or something that is of the highest quality, one might say "of the first water." However, there are many synonyms that can also be used in this context. For example, one might describe something as "top-notch," "exceptional," or "outstanding." Similarly, one might say that a person is "brilliant," "magnificent," or "remarkable." Other synonyms for "of the first water" include "unparalleled," "unbeatable," and "supreme." Ultimately, the choice of synonym will depend on the context and the intended meaning, but all of these words convey a sense of excellence and superiority.