Thank you Kat.

Two of the best operas that don't have creaky librettos or plots are:

Otello by Giuseppe Verde and Boito (librettist)

The Counsel and Amahl and the Night Visitor by Gian Carlo Menotti.

Maybe The Magic Flute could be placed in this category (an afterthought)

There may be more that have dramatic credibility but not too many.

I might include Porgy and Bess as well as Sweeney Todd as important operas
with engaging librettos.

One could argue that the American Musical has made strides in combining sincere drama with music, for example West Side Story.

Opera is nevertheless highly entertaining if 1. you see it live and 2. if you have a way of following the text.