Luffy took the most but Sanji is second to him... he was beaten twice... unlike zoro actually got allmost every bone of hes cracked... hes exosceleton made him recover but the pain he felt beats that of anyone alse too.... Zoro basically fainted not from damage but from 2x pain of hakai he received.... what a wuss he become after timeskip, Oda can only fix him by making him recover slightly faster than luffy , but if we will see him dying that will just be emberacing....
Luffy, Robin, Nami, and Sanji have felt the most pain, IMO. Luffy losing Ace/all the damage he's taken through the series. Robin's horrific life history, combined with Spandam abusing the hell out of her in Enies Lobby. Nami being forced to work for the man who murdered her mother to save her village, only to be backstabbed again after becoming everything she hated. Sanji being treated like a broken soldier as a child, then nearly starving to death on an island, only to have his family come back years later to try to ruin his life again.
Franky, Chopper, Brook all have messed up backstories, too. And Yamato? You spend your entire life having your dad beat you up and kill anyone you become friends with. Lord. The Straw Hat pirates have been through a lot.