Orochimaru is by far the most ruthless. Orochimaru not only used other's bodies so that he can later take it over, but he went from body to body to be able to extent his life and gain his youth back. Not to mention he created a better version of the Kuchiyose: Edo Tensei (Summoning Jutsu: Reanimation). Orochimaru killed his master (3rd Hokage) before Pain killed his master (Jaraiya), and Orochimaru said that the only reason he left Akatsuki is because he was no longer the strongest one when Itachi showed up.
Orochimaru was constantly trying to get his hands on the Sharingan and if Itachi didn't kill the clan than Orochimaru would have done it like Danzo. Orochimaru will cause people to serve him even to death and upon their death Orochimaru would just be like, well, I didn't need them anymore anyway. Orochimaru is brutal and worth than Pain. Pain focused on his hatred towards Hanzou and anything connected to him.
Orochimaru would toy with the people's lives and emotions, experiment on them, imprison people in his hideouts, kill his subordinates, gather people for death as practice like when Sasuke defeated over 100 men and Orochimaru said he was too soft for not killing them, possess people's bodies, then reincarnate the dead to make them his battle slave over and over again.
Orochimaru was constantly trying to get his hands on the Sharingan and if Itachi didn't kill the clan than Orochimaru would have done it like Danzo. Orochimaru will cause people to serve him even to death and upon their death Orochimaru would just be like, well, I didn't need them anymore anyway. Orochimaru is brutal and worth than Pain. Pain focused on his hatred towards Hanzou and anything connected to him.
Orochimaru would toy with the people's lives and emotions, experiment on them, imprison people in his hideouts, kill his subordinates, gather people for death as practice like when Sasuke defeated over 100 men and Orochimaru said he was too soft for not killing them, possess people's bodies, then reincarnate the dead to make them his battle slave over and over again.