I feel like Mariah has a few "big" moments. As someone who has been a hardcore fan since the Butterfly era, I'm biased from 1997 and on. So I'd say The Emancipation of Mimi i.e. The Comeback era. It was incredible, the press was overwhelmingly positive, she could do no wrong and had 3 huge hit singles and winning at the 2006 Grammy's and her performance. Such a great time to be a fan.