Lewis would definitely beat both at his best but you're right in he doesn't give most if any an easy fight but this version of Lennox Lewis, in the fight totals below absolutely batters both of them, with no question about it whatsoever on that night he's miles ahead of both...
View attachment 141060
Lennox Lewis in that first fight against Holyfield nearly landed more in just power punches alone, than either Usyk or Fury landed in total during both these fights...
View attachment 141061
View attachment 141062
He was far more well conditioned than both of these guys in a much stronger era to suggest otherwise would be a joke, he hit with more accuracy and power than anybody Usyk has fought and had faster hands than Fury.
Fury despite losing both fights very fairly caught Usyk with a few clean uppercuts in that first fight, those uppercuts are meat and drink to Lewis he'd have dominated the centre of that ring, he'd also pulverised Usyk with those shots even if he had the toughness to pull through.
He's got a great entertaining style Usyk and it's a throwback to more well rounded heavyweight fighters of the past, despite really liking him though he's nowhere near the greatest heavyweights who've ever lived.
Usyk definitely struggled with energy against Daniel Dubois after he went to the body before Dubois then took that knee, this is despite Dubois himself before that fight having question marks over his own conditioning.
Chisora on Usyk's debut at heavy gave him problems to the body and drained him a fair bit even if it was one sided, he's great to watch but the thing is Usyk just stands out amongst a load of slow plodders nowadays.
Against serious pressure fighters of the past like Joe Frazier or Rocky Marciano tough guys who didn't care about taking a few digs to hurt their opponent, guys who cut the ring off expertly and don't stop punching to the body, in my view Usyk wouldn't do well and certainly appear more tired and unable to move as well.
It's bizarre to say this after seeing his torso but Fury is comfortably the most well conditioned fighter (stamina), that Usyk has fought at Heavyweight that's how much the division has tanked.
There's no question that he's a great boxer technically and aesthetically pleasing to watch Usyk, but Lennox Lewis and Larry Holmes would dominate him with their jabs alone they were both better conditioned too, Ali is better at absolutely everything but despite saying what I've said Usyk is still a great fighter, I'd rank him as probably holding his own in most eras but he's not as great as many people would have you believe though.