Fury:
Height, weight and reach advantage. Smart boxer with skills, but untested other than Wilder who doesn't have the tools to beat him unless he can knock him out. Since beating a washed up Klitschko six years ago Wilder has been his only legitimate opponent. Relaxed in the ring and helps reduce fatigue because of his skills, but his weight could be a liability against a skilled opponent.
Wilder:
His best asset is heart and power. Body type not ideal for a heavyweight. Super heavyweight torso on light heavyweight legs. Lack of boxing skills causes early fatigue against skilled opponents and limits his ability to finish a hurt fighter. Other than Fury has not fought a legitimate opponent the last six years. Helped Ortiz become overrated because of his two fights with him.
Usyk:
Untested chin at heavyweight. Outstanding boxing skills allowed him to avoid Joshua's best shots. Quicker on his feet than any top heavyweight and knows how to move his head and throw when he is in position. Seems to be a real fighter not a $$ marketing machine. Smart fighter like Fury that limits fatigue. He knows when to take a breather and not let the opponent take control of the fight.
Joshua:
Good power. Eddie $$ marketing machine. Limited boxing skills fatigue him against skilled fighters. Too robotic and tight allowing him to get hurt by punches too easily, but good conditioning keeps him in fights. Overrated because of his win over a 41 year old washed up Klitschko. Seems to have an amateur boxer, learn as you go mentality not suited for a champion.
Ruiz:
Durable with power and a champions heart before winning the title which earned him tremendous respect. Now that he is wealthy can he still get off the canvas and fight like the poor Ruiz? Issues with keeping weight down may limit quality training. Fights best after he is hurt which was proven in the first Joshua fight and Arreola fight. His 6'1" height and weight limits his effectiveness unless he is in great shape to push the pace with taller fighters.