What is the most integrated Drupal 7 shopping cart for CiviCRM?
yes Eileen at Fuzion is working towards pulling together Commerce + CiviEntities + Rules as a more flexible approach. We have clients using both Commerce_CiviCRM and uc_civicrm and have had some grief with both of them, such as in terms of when should it update civi addresses and when shouldn't it and clients wanting different outcomes etc. Or eg can customer buy a Membership as part of the cart and get instant member discount on other items in the cart. Hence us going for a more flexible solution.
But to more directly answer your question, starting now I would go down the  Commerce path.