Nah.... Pain was the most impactful for me....... Orochimaru was just this creepy guy after power. Cliched bad guy stuff.
Pein was also cliche, typical old apprentice turned evil and typical villain with god power.So this is no argument :/
Even so I still liked him and how he presented an challenge to Naruto even if he was lamely defeated by a TnJ
Orochimaru though...that guy back then, he was evil not because of some hidden reason but just for the sake of being the strongest, if Kishi had followed up with him there's no way he would be a victim of the TnJ