Of the operas listed, I would go with Carmen, Rigoletto or La Traviata. Both Rigoletto and La Traviata are great choices, two of Verdi's best-known works with plenty of recognizable tunes. They are also dramatic and engaging on the stage. Carmen is also quite fun, with several arias you will recognize. I'd probably pass on Armida and Iphigenie, which are a bit more challenging. Lucia, Romeo and Magic Flute are also not bad options. If you're going to go French, I'd go with Carmen first, since it's a bit more accessible, but Romeo is a perfectly fine option as well. Magic Flute is, as was stated above, a bizarre Masonic fantasy, and if you choose it, definitely be very familiar with the plot beforehand, as it is quite confusing and convoluted. I love Lucia, and as Bel Canto operas go, it is quite accessible, with some wonderful melodies and the show-stopping sextet/mad scene toward the end. As others have stated, do be sure to listen through at least highlights from the opera before you go. I like to buy a recording and listen through with the libretto a few times to become very familiar before I go, so I can focus on the performance on stage and not always have to be looking back and forth from the supertitles above the stage. That's just my approach. Above all, have fun. People often take opera too seriously to enjoy the beauty of the music and the dramatic spectacle. Whatever you choose, just make sure that when the curtain rises, you relax and enjoy the show.