Finished! Okay, here's the completed list. I trust I'm not the only one who spies one or two unfamiliar items...? Big surprises for me are the relative lack of Beethoven sonatas and SQs and no symphony 3 or 6, no Bartόk CfO or concertos, the low number of Mahler and Bruckner and Sibelius works, no Mozart piano concertos, no Verdi operas, and very little post-modern music.
The GMG Essential 100
1 Anonymous Ludus Danielis Estampie-Munich Ensemble
2 Bach Cello Suites Fournier
3 Bach Sonatas & Partitas for Violin Enescu
4 Bach Goldberg Variations Hantai/Mirare
5 Bach St Matthew Passion Fink/Goerne/Harnoncourt (2001)
6 Bach Well-Tempered Clavier Tureck/DG
7 Bartόk Wooden Prince Boulez/CSO
8 Beethoven Symphonies 5 & 7 Kleiber/WP
9 Beethoven Piano Cto #5 Kempff/van Kempen/BP
10 Beethoven Pathetique Sonata Moravec
11 Beethoven String Quartet #14, op 131 Busch Quartet
12 Beethoven Missa Solemnis
13 Beethoven Symphony #9 Furtwängler/London Philharmonia (1954)
14 Berlioz Symphonie Fantastique Davis/LSO
15 Berg Chamber Cto Boulez/Barenboim/Zuckerman
16 Bloch Evocations Sedares/NZSO
17 Brahms Symphony #4 Reiner/RPO
18 Brahms Piano Cto #1 Gilels/Jochum/BP
19 Brahms Piano Trios op 87 & 101/Clarinet Trio Op.114 Beaux Arts Trio /Pieterson
20 Brahms String Sextets Amadeus Quartet et al
21 Brahms German Requiem Kempe/Gruemmer/Fischer-Dieskau
22 Bruckner Symphony #7 Karajan/WP
23 Chopin Études Pollini
24 Chopin Nocturnes Arrau
25 Copland Appalachian Spring Orpheus Chamber orch
26 Debussy Chamber Music for Woodwinds (+ Saint-Saens) Bennett/Gough/et al
27 Debussy Preludes Bks 1 & 2 Michelangeli
28 Debussy Prélude...faune, Jeux, Images, Danses Baudo/Czech Phil
29 Dufay Isorhythmic Motets Huelgas Ensemble
30 Dvořák Symphonies 8 & 9 Mackerras/Prague
31 Dvořák Cello Cto (w/Elgar cello cto) Fournier/Szell/Wallenstein/BP
32 Dvořák Symphony 7 / The Water Goblin Belohlavek/Czech Phil
33 Durufle Requiem (w/Faure Requiem) Barley/Bar/Murray/Cleobury/ECO
34 Gluck Orfeo & Euridice Jacobs
35 Godowsky Studies on the Etudes of Chopin Hamelin
36 Grainger Country Gardens (+ works by Coates) Fennell/Eastman-Rochester Pops
37 Handel Messiah Christie
38 Handel Heroic Arias Bowman/King
39 Haydn 11 Keyboard Sonatas Brendel
40 Haydn String Quartets op 76 Quatuor Mosaïques
41 Hildegard A Feather on the Breath of God-Sequences and Hymns Kirkby, et al
42 Janáček Cunning Little Vixen Mackerras/WP
43 Ligeti Etudes, bks 1-3 Aimard
44 Liszt Favourite Piano Works Bolet
45 Mahler Das Lied von der Erde Ludwig/Wunderlich/Klemperer
46 Mahler Symphony #5 Dohnanyi/CO
47 Mahler Symphony #9 Bernstein/RCO
48 Martin Der Cornet/Die Weise von Liebe und Tod des Cornets Lipovsek/ORFSO/Zagrosek
49 Martinu Symphony #4/Piano Cto #4/Tre ricercari Turnovsky
50 Massenet Mélodies Kruysen/Lee
51 Medtner Sonata op. 25/2, "Night Wind"
52 Mendelssohn Violin Cto (w/Shostakovich Violin Cto #1) Hahn/Wolff/Oslo Philharmonic
53 Monteverdi L'Orfeo Pickett
54 Monteverdi Vespers Bernius
55 Mozart Don Giovanni Jacobs
56 Mozart Cosi fan tutte Böhm (1953)
57 Mozart Late Symphonies Harnoncourt/RCO
58 Mozart Great Mass in C minor Leppard (EMI)
59 Mozart Requiem Böhm/WP
60 Mozart Clarinet Concerto and Clarinet Quintet Frost/Oundjian/Amsterdam Sinf
61 Mussorgsky Boris Gudunov Abbado/BP
62 Pärt Tabula Rasa/Fratres/Cantus Kremer/Jarrett/Sondeckis
63 Pärt Kanon Pokajanen
64 Pergolesi Stabat Mater Alessandrini/Concerto Italiano
65 Prokofiev Romeo and Juliet Maazel/CO
66 Prokofiev War Sonatas Richter
67 Puccini Turandot Pavarotti/Sutherland/Mehta
68 Rachmaninov Piano Cto #2 (w/Tchaikovsky Piano Cto #1) Richter
69 Rachmaninov Vespers Svechnikov/USSR Nat'l Choir
70 Rameau Keyboard Works Tharaud
71 Ravel Piano Trio Rouvier/Kantorow/Muller
72 Ravel Daphnis et Chloe Dutoit/Montreal
73 Satie Selected piano compositions Aldo
74 Schoenberg 5 pieces op 16 (w/ Webern & Berg) Levine/BP
75 Schubert String Quintet in C major Emerson or Melos SQ w/Rostropovich
76 Schubert Sonata in G, D.894 Richter
77 Schubert Schwanengesang Munteanu
78 Schumann Kinderszenen/Kreisleriana/Carnaval Cortot
79 Schumann Symphony #4 Furtwängler/BP
80 Schumann Dichterliebe Wächter/Brendel
81 Shostakovich String Quartet #8 Emerson or Borodin SQ
82 Shostakovich Symphony #7 "Leningrad" Ančerl/Czech Phil
83 Sibelius Symphony #5/Violin Cto Haendel/Berglund/Bournemouth
84 Sibelius Symphony #4 & #7/Tapiola Maazel/WP
85 Strauss Four Last Songs Janowitz/Karajan/BP
86 Stravinsky Rite of Spring Bernstein/NYPO (1958)
87 Stravinsky Symphony of Psalms (w/Poulenc & Bernstein) Bernstein/LSO/NYPO
88 Stravinsky L'oiseu de feu (complete) Rattle/CBSO
89 Suppe Overtures (w/ Auber Overtures) Paray/DSO
90 Tallis Spem In Alium/Salve Intermerata Summerly/Oxford Camerata
91 Tchaikovsky Violin Cto (w/Brahms Violin Cto) Heifetz/Reiner/CSO
92 Tchaikovsky Swan Lake Svetlanov
93 Tchaikovsky Piano Trio op 50 (+ Shostakovich Piano Trio #2 op 67) Argerich/Kremer/Maisky
94 Vaughan Wms Symphony #5 Previn/RPO
95 Verdi Requiem Toscanini/NBC (1951)
96 Victoria Requiem 1605 Christophers/The Sixteen
97 Vivaldi Vespri per l'Assunzione di Maria Vergine Alessandrini
98 Wagner Tristan und Isolde Böhm (1966)
99 Wagner Der Ring des Nibelungen Solti/WP
100 Weber Der Freischütz Keilberth
Edit: typo corrected