An opera I have thoroughly enjoyed is "Boris Godunov," Mussorgsky's masterpiece.
I have three versions on DVD, Kirov Opera of St. Petersburg, Bolshoi Opera, and the original 1869 version, De Nederlandse Opera, as staged in Barcelona. The first two were re-orchestrated by Rimsky-Korsakov. All three are excellent, but I would have liked to have heard Nesterenko of the Bolshoi production in the original as recorded in Barcelona. Robert Lloyd, Boris in the Kirov presentation, was a surprise to me, a non-Russian in a very Russian opera.

I have recently re-listened to "Le Bourgeois Gentilhomme," not a real opera, but a musical comedy ballet with text by Molière and music by Lully, originally staged in 1670 and directed by Vincent Dumestre, Alpha 700 DVD. It tells the tale of a countryman who comes to the city and wants to learn how to be a "gentleman."