"Those are the top two I would say [I've been in the ring with]. In terms of boxing brain and smarts, it's probably Usyk. In terms of athleticism probably Wilder," Chamberlain said.
"He's powerful, very powerful. I remember I sparred him when I was 19, he hit me with an uppercut, I thought I was back in London. He's a solid puncher," Chamberlain laughed.
Chamberlain believes the time he has spent sparring some of the best boxers in the world - inside the best gyms - will certainly develop him as a boxer. He is determined to showcase the skills he's acquired in his July 30 showdown with Chris Billam-Smith in Bournemouth, live on Sky Sports.
"He might have been a cruiserweight but he's gone up and he does have power. So to go in and just try and bomb him, it's not going to make sense. There's punches coming back. You have to be very calculated with your approach.
"Sometimes you have to look at yourself in the mirror and think what can I do to get better?.
"I'm putting everything into my training.
''So it's going to be a great spectacle on July 30 and I can't wait to do the same thing I've been doing but on a bigger scale and showing everyone that Isaac's one of the most improved fighters in recent times."
The Ukrainian became the undisputed champion at cruiserweight before moving up to heavyweight to beat Anthony Joshua for the unified IBF, WBO and WBA titles.
"One million percent,'' he told Sky Sports News.
Chamberlain has also spent time in the ring with another leading heavyweight, Oleksandr Usyk.
''Am I just going to stay here or am I going to try and evolve and better myself? I believe that that's what I've done. I went away, I went to Miami and sparred with all the world champions and world title contenders in Miami just by myself.
Wilder completed a thrilling trilogy of fights with Tyson Fury last year. He lost their final, bruising encounter in Las Vegas in October and the American is yet to unveil his plans for a comeback.
It gives Chamberlain an informed perspective on the Usyk vs Joshua rematch.
''I spent Christmas there, I spent New Years there, I spent my birthday there. It was very, very tough for me but I knew something was going to come out of this.
Chamberlain, a former training partner of Wilder's, expects the American to return to prominence in the heavyweight boxing scene.
"There's method behind the madness."
"I remember I was facetiming him before the other fights, he was in the zone and locked in. A true test of character is how you bounce back."
"People always say it's his power. It's not really, it's his speed. He's very quick off the mark and he processes very quickly. People don't realise it and people only think he's wild just in general.
"AJ has to come with the correct gameplan. He has to come very ferocious, very strong. Everyone keeps saying you have to steamroll Usyk but the thing is Usyk is powerful as well," Chamberlain said.
''Usyk is a great guy, he was giving me a lot of advice on what to do and how to develop my boxing skills."
"So [Joshua] has to be smart. Use his feints, use his lateral movement. Go where Usyk's going but kind of play chess with him but play chess with him aggressively. That's how he has to beat him and wear him down to the body. When you're on the inside be a lot rougher as well. He has a good team around him that will have a great gameplan so we'll see."
"You need characters like that in boxing, he'll be back.
"No, he's only wild when he has you hurt. But he sticks to the basics very well, he's very, very sharp. So he's better than what people think.
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From sparring together, Chamberlain knows Wilder has the tools to challenge anyone in the division.
Deontay Wilder will return to the top of the sport, predicts London cruiserweight Isaac Chamberlain.
''When I fight now, all of the energy that I put into my training, I put it into the fight.
"He [Usyk] is very smart. It's always a chess match.