Weaver weighed 202 pounds when he fought Holmes and gave him a tough go. Walcott weighed 196 pounds for Marciano 1. Only a 6 pound difference
I mean, yeah and he was beaten by a career LHW making his heavyweight debut. Holmes is the most absurdly, ridiculously overrated fighter of any weight class. Most have him in the top three, and some claim that is h2h #1. Based on what? His wins over 35 year old e-mail champ Norton, or 13-fight novice Witherspoon? The wins aren't there. If you think Holmes is a top-five heavy, you really need to take a look in the mirror about what your standards are.
I've been around Mike Weaver a lot, going back to the 1970s, well before he fought Holmes. I was a little kid when I first saw him and don't remember anything about him but, around the time he fought Holmes, we were the same height. He seemed huge otherwise, but him fighting at 202, 210 makes sense. A lot of very muscular, very lean guys weigh a lot less than you would think.
On pure accomplishment... Ali Louis Lewis Marciano Frazier or Foreman Head to head, a lot harder as it is all speculative, but maybe Lewis Ali Usyk Tyson Holyfield or Foreman (depending on the Evan Fields calculation) Holmes has neither the big wins to get there on accomplishment, nor to prove the tremendous head to head. And before anyone tries to play the 20 defenses card, or chop down Usyk being on my list, Holmes never unified for fought a #1, so in my book, Usyk has already proven far more.