Opposite words for annoyance:
joy, gratification, esteem, satisfaction, pleasure, desire, affection, benefit, soother, blessing, approval, smoothy, charmer, solacer, comforter, delight, appreciation, treat, enjoyment.
Usage samples:
  1. He has gained the everlasting annoyance of an otherwise charming neighbour, Max.
    "Max Carrados", Ernest Bramah.
  2. This he heard from the barber's wife, who expressed great annoyance at it.
    "Anecdotes & Incidents of the Deaf and Dumb", W. R. Roe.
  3. She had a slight annoyance this morning- I do not know what old book she had set her heart on.
    "Cosmopolis, Complete", Paul Bourget Last Updated: March 3, 2009.
  4. Jeff, however, was perfectly unconscious of being the cause of their annoyance.
    "The Comings of Cousin Ann", Emma Speed Sampson.