Between Bella and Edward, their flaws made the plot for Eclipse. Edward with his overreactions and Bella with her lack of self knowledge. If Bella had known she loved Jacob and if Edward had not overreacted and been more honest with Bella by telling her how he felt about Jacob (he was jealous and thus insecure), Eclipse would probably be my favourite. Yet, alas, the characters kept their secrets from each other and in certain cases from themselves.
If Edward had been honest with Bella, maybe she would've understood she loved Jacob, and it would have solved a lot of problems quicker.