To be honest, both are really really pretty, it just basically depends on what sorta "girl" you like. For me, it would have to be Jennifer, however, Melissa George is very very pretty, too.
To me Melissa is prettier. She is stunning, I love her hair, she has a flawless skin and her body is really perfect. Plus the accent is really sexy too.
Jen's okay, but in my eyes she is nowhere near as pretty as Melissa.
I'm going with the diplomatic answer and I'm gonna say that both women are beautiful in their own way. I think Jennifer is a gorgeous natural beauty (with the best smile in the world), and I think the same about Melissa, that she's a natural beauty.