Can't decide between Madara, Sasuke or Kabuto...Seeing as no one has talked about Madara, I'll go with him.
1) He's thoroughly uninteresting and thusly undeserving to be one of the final villains.
2) I thought the Third Raikage's power level was bad, but I mean come on, this is just ridiculous.
3) The usual Uchiha plot warp: only his body was restored to its prime, five Rinnegan eyes in total to go around (although that may just be the Edo Tensei, I still find it laughable), he 'took Hashirama's DNA' which is a fairly complex procedure which can only be done in controlled environments, he survived long enough to met Obito, who just happened to get crushed right at his secret hideout and he had time to set up everything to prepare for his plan when he was an ancient man, like giving Nagato his eyes WITHOUT HIM KNOWING.