So reading this manga it seems none of the big antagonist are really ever the bad. So who would anyone think is the msot evil villian in naruto?
Madara plan using tsukiyomi is actually to bring peace and stop the fighting. Obito's too. Nagato wanted a chaos to occur over now and again to teach people lesson which gives a temperamental peace.
Kabuto is seeking to be acknowledge and known by people and was actually really really upset when his motherly figure died (killed by him).
Danzou wanted konoha to be strong and did what he think was best for the village.
Orochimaru iosn't really that evil because he is just a guy obsessed to learn and master every single jutsue. He is doing immoral things but it was never truely for the fact of wanting to establish total dominations and things like purely want to hurt, kill put other in misery etc. He is kinda like an individual wanting to build the ultimate, best piece of work but he is willing to do anything to accomplish it. He is a guy who will follow what interest him. Currently right now he is interested in sasuke so if sasuke is good then he is a good person, if sasuke is evil then he is evil as he is supporting him.
Hanzou a feared guy and infamous actually wants nothing more than peace and in fact is a very honorable guy.
If we look at other akatsuki, kisame is a loyal guy.
Deideria though is twisted and all, even he shows respect to people such as sasori.
Kakuzu is a money guy, he doesn't really care about anything other than money. Before in the past the poor guy was following orders from his village and they were actually being unreasonable to punish the guy for failing to kill hashirama considering what we seen this guy can take down most people. But anyways he is a money guy so i'm sure if he is offered enough money he go do good deeds too. Besides he is a bounty hunter he probably end up killing a lot of bad guys too such as those having money on their heads as missing nins.
Hidan probably a truely evil one. Might have a win here. Since he seems to enjoy nothing more than torturing others.
looking through all of the villians I think the winner is
Probably many forgot who this fellow was but he is a minor villian who employed zabuza to kill the old man building the bridge that is now known as great naruto bridge. He had no morals, all he cared was building his fortune and will stop at nothing to increase his power. He does dark business I think including drugs etc, killing innocents and if anyone who dares oppose him he even goes tot he length of having them killed in public to establish his power and make a point for the people. He is willing to turn agaisnt any anyone and when zabuza was done for he will have his employed men go kill him too because he will then not have to pay him which saves him some cash. The man have no morals whatsoever, its all about himself, money and he will do absolutely anything to increase his influence, money. Despite being extremely rich as you can tell the guy still wants zabuza dead because he will save money! So yeah he is probably the ultimate msot evil villian in the whole anruto series so far!
To be honest I think we need more villians like him in the manga, except he needs to be a bigger villian and perhaps having a main powerful antagonist adopting such personality. It makes things probably more interesting and for once we can truely say to the villian "you deserve to this!".