I thought we just done this. Lewis, Ali, Foreman, Maybe Bowe, maybe Holyfield, maybe Holmes possibly Louis, Vitali, unlikely Wlad I think H2h Tyson's top 5. But it appears there are a number of posters that have him as being unbeatable.
Lewis has the best shot (slight favorite). Holyfield might be second most likely (near even money). Liston, and Vitali would be in the ballpark. I don't favor Ali anymore given his average power, lack of bodywork, and vulnerability to left hooks. I never favored Foreman (wide open) or Louis ( undersized and fought too long ago),
There's actually a fair list of fighters that could do it. But, it has to be said, if there was a "pick a fighter to knock out ATG X" thread, prime Tyson would also be on THEIR list.