Explanation:

- "Of favorable opinion" suggests a positive view or judgment about someone or something. It doesn't relate to quality or origin.

- "Of ancient origin" implies something comes from a long time ago. It relates to the history or age rather than quality.

- "Of the best quality" means something is of the highest standard or excellence. This is the correct meaning of the idiom "of the first water," often used for gems or diamonds.

- "Of no significance" means unimportant or not noteworthy. This doesn't imply quality or origin.

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