I'll have to agree with Billy on this one. Nadine is definitely my favorite Peggy, and I've seen a few of them. I think the two major differences in Nadine's portrayal that make hers my favorite are her genuine portrayal of the character and the fact that she can actually sing. She's also the only Peggy I've seen whose confidence visibly increases as the show progresses and she comes into her own, and she gets laughs in places where none of the others ever did, particularly right before Go Into Your Dance where Annie says, "Hey, kid! You're good!" and Peggy replies, "I know!"
I adore Beth's performance as Dorothy Brock. The singing voice she uses, from what I understand from people who have spoken to her, is a character choice. She will never have Christine Ebersole's golden voice or her elegance, but she is hilarious and is always in the moment.
"Peace! The charm's wound up."
--Macbeth