Is of the nicest correct English?

"Of the nicest" is not grammatically correct in standard English.

Here's why:

* "Nicest" is already a superlative. It means "the most nice," so you don't need to use "of" to indicate a comparison.

* "Of" is usually used with comparisons like "one of the nicest." This indicates that there are multiple nice things, and you are referring to one of them.

Here are some correct ways to express the idea:

* "One of the nicest"

* "The nicest"

* "Very nice"

* "Extremely nice"

The best option will depend on the context of your sentence.