Should the noun be singular or plural in the expression "...one of, if not the, [superlative] [noun]..."?

Question

A common English expression takes the form of "It was one of, if not the, best experience[s] of my life." In this expression, what is the correct number for "experience[s]"?

Answer 1

In that sentence, the clause "It was one of the best experiences" is divided by the (technically optional) phrase, "if not the," which is indicated by the commas. Leaving the noun in the singular would result in the sentence sounding like, "It was one of the best experience of my life" if you were to remove the optional phrase.

A shorter way to answer your question would be to point to the use of the words "one of," indicating that one is recalling the memory of a singular experience; but, since it uses "one of," it has to be one of many, therefore the proper way is to use the plural form of the noun. I hope this answers your question!