Turandot for me. Well anytime she is paired with Corelli. Nilsson is a singer that I rarely listen, but certainly with an amazing voice. Nilsson and Corelli really made a great pairing. Although Corelli was great with many other sopranos like Callas and Tebaldi. I love this video where Corelli suprises Nilsson in a talk show.

https://www.youtube.com/watch?v=ZDo8d12_yHU

There are other videos of this talk show appearance in which Corelli sings L'ultima Canzone. He sounds better than late in his career. I guess he could finaly relax and not be a nervous wreck about performing. It always amazes me that someone who is so talented could be so nervous. Well we are all human in the end. This was filmed in 1981 so his voice did improve after he retired.