Here's how the biggest titanosaurs rank out in first-last place:
1. Tie between Alamosaurus (referred Mexican fibula + Fowler & Sullivan's neck centrum), Puertasaurus (1 cervical, 1 dorsal, 2 unpublished caudals) and the "Chubut Monster" (majority of skeleton from at least six specimens). All of of these animals appear to top out around 120+ ft. long and probably 100 tons.
2. Tie between Argentinosaurus and the "MLP Monster" (briefly mentioned by GSP, 1988 with estimate measurements, and lost to history since). Both of these animals were probably pushing 110+ ft. long and 80-90 tons
3. Tie between Ruyangosaurus (cervical rib, anterior and posterior dorsals, additional unpublished dorsals, dorsal rib, upper femur, tibia), Notocolossus (dorsal and caudal vertebrae, foot, and limb elements) and "Argyrosaurus" sp. (the larger referred femur FMNH 13018)