Pretty sure it's gonna be Luffy. Ichigo will have the upper hand at first and knock Luffy down, while Luffy won't get back up. Then when Ichigo thinks he won and turns around, Luffy's gonna whip out his massive dong and make it stretch so far until it goes inside Ichigo's ass, but he's not gonna stop there. He's gonna make it keep stretching until it comes out through Ichigo's throat with a f**k ton of blood, and Ichigo will already be dead because that cock pierced through Ichigo's heart. I mean, you've read One Piece. You know what Luffy usually does to people