just about anything sung by Renee Fleming.
Good call. Opera performances come to mind and there are few references here. While I do not consider myself an authority of any kind in re opera, i’d say any reasonable fan would suggest an aria by Maria Callas.
While I can’t pop off opera singers on a whim, I’d say any well sung Queen of the Night ari in the Magic Flute night perhaps humble a few singers in this thread. Ditto a well sung count Aviveno in Esci omai, garzon malnato in il nozze di figaro.
it is my understanding Don Giovanni has some of the best bass singing of all time.