Alice, hands down. She's so positive, happy, kind and smiley :) And she has such a beautiful bond with Jasper.
After I found out about Rosalie not giving a care to Bella's life and only supproting her because she wanted to get her pretty hands on the baby! I have lost respect for her, she is really quite selfish and self-centred, also mean and un-deserving of Emmett's love. She'd give him up just to be human, if she loved him as much as Bella loves Edward then she'd do anything, be anything for Emmett. But she wouldn't.