I agree with Jagugar, Kibagami Jubei all the way. He used an awesome blend of intelligence and skill to defeat enemies. Not to mention he took down Genma and his special technique&I base my observations the Ninja Scroll movie and not the TV series. I would agree that a close second would be Kenshin (got to give it to the Battosai and the way of the Hiten Mitsurugi) followed by Zaraki Kenpachi...I just love the way he takes on opponents and how he savors the fight (not to mention he is a total badass and that is without using shikai or bankai)!