Do buy all five. Choose one grammar (Hewings or Destination) and one vocabulary/collocations (McCarthy). Supplement with authentic reading (The Economist / The New Yorker) and listen to academic lectures (TED Talks at 1x speed). A C1 book does not teach you C1—your active production of the language in writing and speaking does. Use these books as a workshop, not a library.
Why is this "exclusive" to the advanced learner? Because the narrator, Stevens, speaks in a distinct, highly formal, and repressed dialect of English. The text is an exercise in reading between the lines. Stevens’s language is grammatically flawless but emotionally evasive. For a C1 learner, this is a masterclass in the difference between what is said and what is meant (subtext). c1 english level books exclusive
The standard paperback is good, but the transforms learning. It includes: Do buy all five