When the thought of this list first transpired, it didn’t seem as difficult as it ultimately was. There are so many different aspects to consider when determining who the best heavyweights of all time really are. Especially, when comparing careers that are in different eras.
Lists like the one complied here, come down to personal beliefs and matters of opinion. In fact, you can rearrange the top 3 and there’s not a solid counter-argument to be had. The three most important factors I looked for were: longevity, versatility, and what was their level of competition? When comparing two resumes, it needs to be factored in that MMA math is not a viable comparison for fighters.