1) Verdi: Don Carlos
2) Verdi: Aida
3) Mozart: Cosi Fan Tutte
4) Wagner: Der Ring Des Nibelungen
5) Donizetti: Lucia Di Lammermoor
6) Verdi: La Traviata
7) Rossini: William Tell
7) Puccini: Suor Angelica
8) Puccini: La Boheme
9) Verdi: Rigoletto
10) Mascagni: Cavalleria Rusticana
11) Gluck: Orpheo et Eurydice
12) Berlioz: Les Troyens
13) Bizet: Carmen

The top ten are fairly sure, the last three I could have easily considered: Massenet's Werther, or Donizetti's La Fille Du Regiment, or L'elisir or Tchaikovsky's Eugene Onegin