It is certainly known that the discoveries of some objects may be disputed and thus the list modified. Note we take NGC 5866 as M102 (discovered by Méchain and co- or rediscovered by Messier as well as (later) by William Herschel).
Note: Very recently awareness arose on several additional independent co-discoveries of a number of Messier objects by Johann Elert Bode which are currently worked into this list.
Ordered by score, the original discoverers of the Messier Objects are:
Discoverer Score Objects
Al Sufi 1 31 Aratus 1 44 Aristotle [39?][41] Bevis 1+1 1 (35) Bode 4+14 (2) (10) (12) (15) (29) (33) (34) (37) (39) (43) (48) (50) (51) 53 (64) 81 82 92 Cassini GD [50] Cysatus +1 (42) Darquier 1 57 De Chéseaux 6+1 4 (6) 16 17 25 35 71 De Mairan 1 43 Flamsteed +2 (8) (41) Halley 1 13 Herschel C +2 (48)(110) Herschel W +9 (47) (91)(102)(104)(105)(106)(107)(108)(109) Hesiod +1 [45] Hevelius [40] Hipparchus +1 (44) Hodierna 9+2 6 8 (31) 33 34 36 37 38 41 (42) 47 Homer 1 45 Huygens +1 (42) Ihle 1 22 Kirch 2 5 11 Koehler 3+3 59 60 67 (71) (81) (82) Lacaille 2+3 (4) (6) (7) 55 83 Le Gentil 1+2 32 (36) (38) Maraldi 2 2 15 Marius +1 (31) Méchain 25+4 63 (71) 72 74 75 76 77 78 79 (80) (81) (82) 85 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 Messier 44+21 (1) (2) 3 (5) 9 10 12 14 (16) (17) 18 19 20 21 23 24 (25) 26 27 28 29 30 (32) (33) (34) (35) (37) 39 40 46 (47) 48 49 50 51 52 (53) 54 56 (57) 58 (59) (60) (61) 62 (64) 65 66 (67) 68 69 70 73 80 84 86 87 88 89 90 91 (92) 93 (102) 110 Oriani 1+1 (60) 61 Peiresc 1 42 Pigott E 1 64 Ptolemy 1 7 Winnecke +1 (40)
Total 110
Messier (44), Méchain (25), Hodierna (9), De Chéseaux (6), Bode (4), Koehler (3), Kirch, Lacaille and Maraldi (2 each), and Al Sufi, Aratus, Bevis, Darquier, De Mairan, Halley, Homer, Ihle, Le Gentil, Oriani, Peiresc, Edward Pigott and Ptolemy (1 each).
Independent discoveries, including co-discoveries, of Messier Objects lead to the following ranking:
Messier (65), Méchain (29), Bode (18), Hodierna (11), William Herschel (9), De Chéseaux (7), Koehler (6), Lacaille (5), Le Gentil (3), Bevis, Flamsteed, Caroline Herschel, Kirch, Maraldi and Oriani (2 each), and Al Sufi, Aratus, Cysatus, Darquier, De Mairan, Halley, Hesiod, Hipparchus, Homer, Huygens, Ihle, Marius, Peiresc, Edward Pigott, Ptolemy and Winnecke (1 each).