It is extremely difficult to answer these questions. Firstly, because
responses to recordings (and for that matter, to performances) vary
greatly. Secondly, because there is no *definitive* recording of any of
Wagner's stage works. It is possible to give some suggestions, however,
based on the following assumptions:

 i.  A beginner usually wants a recording in excellent sound, therefore we
 should first consider modern, stereo, possibly digital recordings.  The 
 beginner might wish to explore historical recordings later on, but not 
 first.
 ii. A beginner would prefer to avoid recordings with distracting stage 
 sounds or audience noise.  Therefore many live recordings can be ruled
 out.
 iii. All listeners prefer great singers over good singers, and would
 prefer not to listen to recordings with less good singers.
 iv. If one begins with a recording that employs either unusually fast or
 unusually slow tempi, all subsequent recordings heard will sound either
 too slow or too fast in relation to one's first impression of the work.
 v. A beginner might not want to spend too much money, so we should
 consider recordings that might be available at a discount.  Unfortunately
 this mitigates against recommending the very latest recordings.
 vi. It would also be helpful if the first recording was packaged with a 
 libretto, which the cheapest recordings usually lack.

Taking both the above and newsgroup discussions into consideration, the 
editor of this FAQ makes so bold as to suggest the following as first
recordings.

* _Der Ring des Nibelungen_, studio recording, DECCA/London, 1964.
  Conductor: Sir Georg Solti. Vienna State Opera Chorus and Vienna
  Philharmonic. With Hans Hotter (R,S), George London (W), Birgit Nilsson,
  James King, Régine Crespin and Wolfgang Windgassen. Some consider the
  _Götterdämmerung_ of this cycle to be not only the best Wagner recording
  ever, but the best recording of the 20th century. The Penguin Opera Guide
  comments, "There is not a single weak link in the cast". Recently reissued
  after remastering. See the Wagner Books FAQ for books by John Culshaw, the
  producer of this recording. A beginner might also find useful the CD set,
  'An Introduction to Der Ring des Nibelungen', in which Deryck Cooke
  introduces the leitmotives of this work, using musical examples from the
  Solti/Culshaw recording.

* _Dutchman_, studio recording, Naxos, 1992. Conductor: Pinchas Steinberg.
  ORF Symphony Orchestra, Budapest Radio Chorus. With Alfred Muff, Ingrid
  Haubold, Erich Knodt and Peter Seiffert. A cheap and cheerful recording
  with libretto but no translation. Alternative also currently at budget
  price: Dorati on Decca/London, 1962, with London, Rysanek, Tozzi and
  Liebl, no libretto.

* _Lohengrin_, studio recording, EMI, 1964. Conductor: Rudolf Kempe.
  Vienna Philharmonic Orchestra, Vienna State Opera Chorus. The Swan Knight
  is Jess Thomas. Also with Elisabeth Grümmer, Dietrich Fischer- Dieskau,
  Christa Ludwig (in a much-admired interpretation of Ortrud), Gottlob Frick
  and Otto Wiener. There are some imperfections in sound quality. Reissued
  on 3 CDs (and therefore usually cheaper than sets with 4 CDs).
  Alternative: Kubelik.

* _Tristan und Isolde_, live recording, DGG, 1966. Conductor: Karl Böhm.
  Chorus and Orchestra of the Bayreuth Festival. Recorded in RW's Festival
  Theatre. With Wolfgang Windgassen and Birgit Nilsson in the title roles.
  Also with Christa Ludwig, Eberhard Waechter and Martti Talvela. Although
  the tempi are a little faster than usual (which allows each act to fit on
  a single CD) and the orchestral playing is not always perfect, this is
  widely regarded as one of the best 'Tristan' recordings. There is no
  audience noise and very little stage noise. Recently reissued after
  remastering. For alternatives, see the new discography by J. Brown.

* _Parsifal_, studio recording, Teldec, 1991. Conductor: Daniel Barenboim.
  Berlin State Opera Chorus and the Berlin Philharmonic. Parsifal is
  Siegfried Jerusalem, Kundry is Waltraud Meier, Gurnemanz is Matthias
  Hölle. Amfortas is José van Dam.  Alternatively, the 1980 Bavarian Radio
  studio recording conducted by Rafael Kubelik.  Parsifal is James King,
  Kundry is Yvonne Minton, Gurnemanz is Kurt Moll, Amfortas is Bernd Weikl.  
  For other alternatives, see the online discography of complete recordings 
  at < http://www.monsalvat.no/discogra.htm >.

* _Mastersingers_, studio recording, Arts Archives, 1967. Conductor: Rafael 
  Kubelik.  Chorus and Orchestra of Bavarian Radio.  There is a broad 
  consensus in the group that this is the all-round best recording of the 
  opera.  Hans Sachs is Thomas Stewart, Walther is Sandor Konya, Eva is 
  Gundula Janowitz.  Although the booklet contains a libretto, there is no 
  translation.