Sorry but the Holmes and Spinks wins are nothing, he took over from a weak era against two badly faded champs. The other ones you list are good, but not great wins.
Saying they are nothing is drivel. Spinks was undefeated. Holmes was only beaten by Spinks, he afterward went on to beat Ray Mercer and give Holyfield a very tough fight. Either way they were both dispatched in ruthless fashion. Spinks had never been knocked down let alone knocked out. Don't be a revisionist.
'Trevor Berbick was the worst title holder ever' Purity won the WBC International HW title from Wlad. He was a title holder.
Yah Ray was never a good boxer, just a guy with a lot of toughness and power. He also lost to Jesse Ferguson right after losing to Holmes. And Spinks only had like 5 or so heavyweight fights period so the fact that he had never been knocked out before Tyson isn't surprising.
Purrity never held a world title. Would you consider the winner of Chisora v Haye a unified champ? because that fight is for the WBO and WBA internation titles. Berbick was shite and won his title by beating an Old shot to ****, Parkinsons riddled Ali. Holmes was way past his best and Spinks was a very good LHW who beat a passed it Holmes, which doesn't make him a great HW or anywhere near. All that said, Tyson dealt with those guys in impressive fashion and in a way any great fighter should have. Tyson was a great fighter but his CV is ****. Sorry but those are the facts. Had his prime come when he was around 30 like most HW's tend to the opposition was there for him to become one of the best HW's in history. But for all his skill set in his prime he didn't beat anyone which is why he'll never be a top 10 ATG. I think the Douglas fight hurts his legacy badly too.
Berbick> Leon Spinks, Francisco Damiani, Shannon Briggs, and Sergei Liakhovich at any rate. Tyson's defining win at the time was the 91 second decimation of Spinks, who was coming off an impressive victory over a faded but much larger and still somewhat dangerous Gerry Cooney. Holmes would be his best win in retrospect, since he proved he still had something left in the tank by beating Mercer and giving McCall and Holyfield tough fights in subsequent challenges for the belt.