^ How I wish we would get to hear the full song by her.
I prefer Christina because I think no one can deliver such powerful, raw and quite emotional performances like she does. She's not perfect vocally, nor she tries to be (edit: I forgot to mention that I meant
live), it just comes from her heart. Plus her tone is just heaven. (like in 'I Love You Porgy', 'I Am', 'A Guy What Takes His Times', 'Save Me From Myself', 'Without You', 'But I'm A Good Girl', etc.)
But they both are amazing vocalists. They just happen to have different styles.