Personally, I prefer a "20-20" zoom lens, much sharper!
I prefer the 20 mm fixed. Don't like extreme wide zooms anyway, make you dizzy when you zoom from 20 mm to 20 mm.
But give me a 100 mm - 100 mm zoom. Much better than a 100 mm.
And i'm sure there was a photographer at some time somewhere who only used a 100 mm lens (though i'm not quite sure whether it was a "Prime or Zoom").