There are others but this is the who's who of opera. My favorite would be Don Giovanni followed by Wagner's - Ring Cycle. Wagner hated Jews but if we avoided all the scum of humanity that would leave very little of any of the Arts to enjoy.

Mozart

Don Giovanni
Le nozze di Figaro
Cosi fan tutte

Wagner

The Ring Cycle
Tristan und Isolde
Der fliegende Hollander
Parsifal
Das Rheingold

Puccini

La Boheme
Madama Butterfly
Tosca

Verdi

Aida
Rigoletto
La Traviata

Rossini - Il barbiere di Siviglia

Bizet - Carmen