No, not Leah. Nothing against Leah, so don't be offended, but I think Leah and Jacob are good as just friends. Besides, if Jacob had imprinted on Leah, it would have been the first time he saw her after turning into a wolf. Therefore, he wouldn't have tried to tell Bella about the werewolves, therefore, he never would have known Bella was jumping off the cliff. And THEREFORE, Bella would have died, and that would have been the tragic end to the epic Twilight Saga. So, no, Jacob and Leah are better off as friends.