If by better, you mean more effective, as opposed to more skilled, then probably Wlad under Steward. The methods, a combination of distance control, jab and clinching, may have been somewhat rudimentary and not aesthetically pleasing, but they were effective.
Def Wlad rarely got hit against smaller fighters, couldn't afford it with his chin. The others got hit bit too much.
Lewis. Wlad always wrestles. Thats a given , he has limited skills which means he cannot defend himself legally when anyone gets close. Illegal holding , head locks , leaning on backs etc are the only ways he can defend himself. Unlike Wlad, Vitali could fight backing up and keep range. Thats why he never needed to clinch against guys like Peter and Aroella.
Ive called out Lewis for clinching many times. But he was nowhere near as bad as Wlad Lewis would never have looked like this against Peter. This content is protected Or this https://www.boxingnews24.com/2012/03/wladimir-clinched-15-times-in-the-1st-round-against-mormeck/ If the ref doesn't allow clinching , he has no defensive technique..absolutely none.