New to Opera, have some questions

I heard part of Carmina Burana last year and decided I really wanted to buy it. I have a few copies, and recently bought Der Mond.

I also bought a version of Carmen, but the surface noise was too much. I was disappointed because I liked the music, and singing.

I'm wondering what other Opera's people might suggest, and does it make any difference to most listeners if they can understand the language? I like Der Mond because I do speak some German.