Talking about liner notes (those that were not just obvious sales blurb for a brand-new release), I think most people would he hard pressed to decide whose body of work overall was on a higher level - Nat Hentoff or Ira Gitler.
One fact that also came to mind (without wanting to slight the achievements of Nat Hentoff in ANY waY) - I seem to have read somewhere that Hentoff probably would not have been too keen on seeing some of his early record reviews for Down Beat from the 50s being recirculated in later decades. Becauses his assessments had changed. And though I cannot name precise examples right now (I would have to re-read in detail) I remember having felt similarly when reading the early volumes of those Down Beat Record Reviews books. There were instances that left you wondering what his judgment would have been, say, 10 year later.