I prefer the last one. Honestly I don't think numerical stats should be involved at all, just the traits and people's common sense seems good enough to me. A numerical stat system is pretty pointless without dice or some other form of random number generation and a great deal of calculation, because there's no way it can cover all the numerous variables that can come into play with writing--for instance, if you gave us a hard and fast "Bob has 8 Strength and Jim has 10, Jim will always win in a fist fight" Bob could still argue "what if I poison his booze? What if I attack him from behind? What if I shoot a cannon at him?" so on and so forth. 

Plus, One Piece is supposed to be a whacky, ridiculous world. Bogging it down with numbers seems like it would hamper the fun.