Isn't it obvious that Kabuto would be the winner?
Thanks to Orochimaru, he was able to surpass him. He achieved the Ryuu Sennin Modo which increases his perceptional abilities, seemingly grants him unlimited Chakra and increases the level of all his other techniques. He also developed some quite formidable Senjutsu. On top of that he inherited all the powers from Orochimaru's subordinates, the Oto Quintet. He inherited a liquidation ability similar to that of Suigetsu, Karin's healing abilities and even Orochimaru's white snake form. He perfected Manda. Before all those achievements it doesn't matter if he has Kusanagi no Tsurugi, Sanju Rashomon or Mandara no Jin.
Seemingly his only weakness is his cockyness, which also applies to Orochimaru, though.