If the intent is to store text and attributes, maybe
NSAttributedString. But you didn't ask about attributes or formatting, so that's just a guess.
If the intent is to have mutable text, maybe NSMutableString. And you didn't mention mutability or editability, so that's another guess.
Otherwise I'm with dejo: Why not NSString? Who's been bad-mouthing the mild-mannered yet unprepossessing NSString, and where did you read these vile accusations?