If any and all DLC could be included for free I'd probably go with either Fallout New Vegas or Halo Reach. Espcially New Vegas seeing how Fallout 3 kept me occupied for a hundred hours easy and that was before Operation Anchorage and don't even get me started on Hardcore Mode and Multiple paths. And Halo Reach Because its Bungies Last Halo game for either ever or a long ass time and Bungie goes all out with thier post launch DLC support