A prime Witherspoon would unironically be Fury's best win in terms of h2h threat. Wilder didn't have much outside his nuke of a right and his sheer height/athleticism. Wladmir was old and gunshy. That being said, I would still favor Fury but not by a lot. Fury would give Witherspoon plenty of problems with his height, reach, and shuffling gypsy movement. He's a bit unique in that regard as the closest the division ever came to a man that huge able to move around with tricky footwork was Buster Mathis. Fury could also try walking down and smothering Spoon with his Kronk offense and clinching. Gun to my head, I expect Fury to take a close decision in an exciting fight.
Witherspoon KO Fury Fury, big target for that Spoon overhand right. Witherspoon > Wilder Fury goes down (of course) and stays down.
Best of Witherspoon absolutely takes it for me. Fantastic overhand, good body puncher and a legit, accurate power in both hands.
Ability wise Fury is definitely a level or two above. As long he he turns up at his best (like in Wilder 2, Klitschko) there'd only be one winner.