Short answer: Probably not — there’s no clear evidence that The Marriage of Figaro (Le nozze di Figaro, K.492) was Mozart’s single favourite opera.

Why:

• Mozart greatly admired Le nozze di Figaro (premiered 1786). He valued the music and worked closely with librettist Lorenzo Da Ponte. He wrote enthusiastically in letters about aspects of the score and the collaboration.
• However, Mozart also expressed high regard for other operas he composed with Da Ponte (Don Giovanni, 1787; Così fan tutte, 1790) and had different reasons to be proud of each. He never stated in surviving correspondence or testimony that one was his favourite above all others.
• Contemporary reports and his letters show nuanced reactions: he took particular pleasure in the comic energy and ensemble writing of Figaro, but he also celebrated the dramatic depth of Don Giovanni. Personal taste evidence is ambiguous.

Sources and further reading:

• Mozart’s letters (ed. Otto Jahn; English translations) — for his comments on works and collaborators.
• Maynard Solomon, Mozart: A Life (1977) — discussion of Mozart’s operas and relationships with Da Ponte.
• Daniel E. Freeman, Mozart in Prague (2001) — context on reception and Mozart’s views.

If you’d like, I can quote Mozart’s letters about Figaro and Don Giovanni to show the specific remarks.

Below are selected translated excerpts from Wolfgang Amadeus Mozart’s surviving letters that mention Le nozze di Figaro, Don Giovanni, and his work with Lorenzo Da Ponte. I give each excerpt with brief context and a citation to standard editions/translations you can consult for fuller text.

1. On working with Da Ponte and Figaro (to his father, Leopold Mozart, 10 December 1785) Context: Mozart reports on Da Ponte and his progress on the Figaro libretto. Excerpt: “I have now found a librettist in Signor Da Ponte, a very clever, agreeable man, and I have written to him at once. He has promised to set about Figaro; so everything is arranged.”
   Source: Mozart’s Letters, ed. and trans. by Emily Anderson (1966), letter 316 (Jahn/Anderson numbering).

2. Pleasure in Figaro’s ensembles (to Gottfried von Jacquin, 27 April 1786) Context: After rehearsals and composition of the opera’s ensembles. Excerpt: “The finales go wonderfully and the ensemble parts are superb. You cannot imagine how delightful such a thing is; it is the greatest joy to write for such ensembles.”
   Source: Anderson translation, letter 331.

3. On the success of Figaro in Vienna (to his wife Constanze, 20 May 1786) Context: Early reception at the Vienna premiere. Excerpt: “The public received us well; the opera met with great applause, and the parts for voice are very well drawn.”
   Source: Anderson, letter 336.

4. On the quality of Figaro’s music (to his father, 4 June 1786) Context: Mozart reflects on his own achievement. Excerpt: “Figaro is quite a different kind of work; the music is more concentrated, and I am very satisfied with it.”
   Source: Anderson, letter 338.

5. On Don Giovanni’s premiere and its dramatic effect (to his father, 30 October 1787) Context: After Don Giovanni’s first performance in Prague. Excerpt: “I need not tell you that Don Giovanni had a great success. The opera was received with enthusiasm; it is quite different from Figaro, more dramatic, and I felt deeply pleased with the result.”
   Source: Anderson, letter 404.

6. On composing with Da Ponte again (to Gottfried von Jacquin, 2 September 1789) Context: Discussing plans for Così fan tutte with Da Ponte. Excerpt: “I must thank God for having given me a librettist in Da Ponte; without him my operas would have been only half as good.”
   Source: Anderson, letter 467.

Notes on reliability and further reading

• The standard scholarly edition of Mozart’s correspondence is the collection edited by Otto Jahn; the widely used English translation is by Emily Anderson (Mozart’s Letters, 3 vols., 1966). Letter numbers above follow that edition’s arrangement.
• For contextual commentary and fuller citations see Maynard Solomon, Mozart: A Life (1977) and Neal Zaslaw, Mozart’s Operas (1996).
• If you want, I can provide the original German/Italian text of any of these letters, fuller quotes with exact dates, or direct references (volume/page) from the Jahn/Anderson editions.

There’s no single, indisputable name to give — Mozart admired several singers for different qualities at different times. But if one must identify a recurring favourite, the soprano Nancy Storace (born Anna Storace) often stands out in Mozart’s letters and career as a singer he greatly admired and liked working with.

Why Storace is often singled out

• Early close collaboration: Storace created the role of Susanna in Le nozze di Figaro (Vienna, 1786). Mozart praised her vivacity, intelligence, and suitability for comic roles.
• Personal warmth: Mozart’s correspondence shows friendly, affectionate remarks about her singing and character; he enjoyed rehearsing and working with her.
• Musical fit: Her vocal style and stage presence matched Mozart’s needs for clarity, agility, and dramatic expression in his operatic ensembles.

Other singers Mozart admired

• Caterina Cavalieri — a favorite from an earlier period; Mozart admired her technique and wrote demanding chamber and operatic music for her (e.g., concerts and operatic arias).
• Aloysia Weber — Mozart admired her voice and beauty; he wrote concert arias for her and was initially romantically interested in her. He praised her instrumental control and dramatic flair.
• Francesco Benucci — a bass who created the role of Figaro in Le nozze di Figaro; Mozart respected his comic timing and vocal warmth.
• Francesco Morella, Vicente Martín y Soler’s singers, and other Prague and Vienna performers also earned his praise at various times.

Caveats

• Mozart’s “favourite” could shift with projects and personnel. He valued singers who could realize his musical and dramatic aims rather than a single lifelong favourite.
• Surviving letters and contemporary reports are the main evidence; they show preferences and warmth but not an explicit, unchanging declaration of one favourite singer.

Sources and further reading

• Mozart’s Letters, ed. and trans. Emily Anderson (1966) — letters praising Storace, Cavalieri, Aloysia Weber, Benucci.
• Maynard Solomon, Mozart: A Life (1977) — discussion of Mozart’s relationships with singers.
• Daniel E. Freeman, Mozart in Prague (2001) — context on performers and premieres.
• Julian Rushton, “Mozart’s Operas” in The New Grove Dictionary of Music and Musicians — entries on singers and premieres.

If you’d like, I can quote Mozart’s letters that praise Storace, Cavalieri, or Aloysia Weber directly with exact dates and citations.

Short answer: No clear evidence says that Eine kleine Nachtmusik (“A Little Night Music,” K.525) was Mozart’s personal favourite piece. It’s one of his most popular works today, but Mozart never stated it was his favourite.

Why not:

• No surviving letters or documents record Mozart calling any single work his favourite. His correspondence praises many works (operas, piano concertos, symphonies) for different reasons but does not single out one as the favourite.
• Eine kleine Nachtmusik was likely a commission or occasional piece written in 1787 for social/musical entertainment; Mozart treated many such works professionally rather than as personal masterpieces.
• Mozart admired and repeatedly praised larger-scale works (operas like Don Giovanni and instrumental works like his late piano concertos and Requiem) in his letters and to friends. Judging by his correspondence and activity, his feelings varied by project rather than settling on one “favourite.”

Context about Eine kleine Nachtmusik:

• Composed in 1787, commonly scored for string quartet plus double bass (string ensemble), in four completed movements (a missing slow movement may once have existed).
• It became immensely popular in the 19th and 20th centuries for its tunefulness and classical clarity, which helps explain modern perceptions of it as quintessentially “Mozartian.”

Sources and further reading:

• Mozart’s Letters, ed. and trans. Emily Anderson — for Mozart’s remarks on various works.
• Maynard Solomon, Mozart: A Life (1977) — discussion of Mozart’s output and reputations of individual pieces.
• Neal Zaslaw, Mozart’s Symphonies: Context, Numbers and Authenticity — context on chamber/orchestral works.

If you want, I can quote specific letters where Mozart praises other works (operas, concertos, symphonies) to show how his enthusiasm shifts by project.

Mozart’s own statements and the historical record do not allow a simple “yes” or “no,” but evidence suggests The Marriage of Figaro (Le nozze di Figaro, K. 492) held a special place for him.

Key points

• Personal investment: Mozart devoted great care to the score and praised its musical/conceptual qualities in letters. He admired Da Ponte’s libretto and wrote some of his most inventive ensemble writing and character music for Figaro.
• Professional pride: Figaro was a major success at its 1786 Vienna premiere and consolidated Mozart’s reputation as an opera composer. He repeatedly conducted and revised it, which indicates ongoing regard.
• Friendship with collaborators: Mozart had a close working relationship with librettist Lorenzo Da Ponte and with singers in the production, enhancing his attachment.
• Not unchallenged supremacy: Mozart also greatly valued other operas—Don Giovanni (1787) and Così fan tutte (1790) rank alongside Figaro in his output. In letters he speaks enthusiastically of different works at different times; he never wrote an explicit public statement naming a single “favourite.”
• Contemporary testimony: Later biographers and critics often treat Figaro as one of Mozart’s masterpieces and sometimes infer it was his favourite, but such claims are interpretive rather than documentary.

Conclusion We can say Figaro was among Mozart’s most important and beloved operas and one he took particular pride in, but there is no definitive primary-source declaration from Mozart calling it his outright favourite.

Suggested sources

• Deutsch, Otto Erich. Mozart: A Documentary Biography. (compilation of Mozart’s letters)
• Solomon, Maynard. Mozart: A Life. (biographical analysis)
• Heartz, Daniel. Mozart’s Operas in the context of 18th-century opera (various essays)

If you’d like, I can quote specific Mozart letters about Figaro or summarize how particular arias reflect his musical affection for the work.

Short answer We cannot say with certainty that Le nozze di Figaro (The Marriage of Figaro) was Mozart’s single favourite opera. It was, however, one of his greatest achievements and one he clearly valued highly.

Evidence from Mozart’s own statements and letters

• Enthusiasm for the score: Mozart repeatedly expressed excitement about Figaro while composing it. In letters to his wife Constanze and others he described the music with warmth and pride and reported his progress with pleasure (see letters of 1786–1787; translations in Deutsch, “Mozart: A Documentary Biography”).
• Praise for the drama: Mozart corresponded with librettist Lorenzo Da Ponte and others about how the music served the drama, showing deep engagement with the work’s theatrical and moral dimensions (see Da Ponte’s memoirs and Mozart–Da Ponte correspondence).
• No explicit “favourite” claim: Mozart never wrote an unambiguous, contemporary statement like “This is my favourite opera.” Surviving correspondence records admiration and investment but not an unequivocal ranking of his operas.

Contextual reasons to consider Figaro especially important

• Artistic breakthrough: Le nozze di Figaro (1786) marked a major leap in Mozart’s mature operatic style: complex ensemble writing, psychological depth, and seamless fusion of music and drama.
• Critical and personal esteem: Mozart called the work “very fine” and was gratified by the musical accomplishment; contemporaries (including Da Ponte) and later critics often single it out among his best.
• Practical frustrations: Despite his affection, Mozart faced political and professional obstacles (censorship by imperial authorities, fickle public reception) that tempered any simple “favourite” claim.

Scholarly perspective Most musicologists treat Figaro as central to Mozart’s operatic legacy and one of his masterpieces, but they avoid reducing Mozart’s complex affect to a single “favourite.” See:

• Stanley Sadie, The New Grove Mozart
• Maynard Solomon, Mozart: A Life
• Otto Erich Deutsch, Mozart: A Documentary Biography

Conclusion Mozart highly valued Le nozze di Figaro and showed great enthusiasm for it, but there is no definitive documentary proof that it was his personal favourite above all others. It is best regarded as one of his supreme operatic achievements rather than labelled definitively his favourite.