Ranking heavyweights across eras requires admitting two things at once
Rico Verhoeven’s reign is genuinely dominant and the division he dominated is thinner than the one Hoost, Aerts and Schilt worked through. Both are true.
Any honest attempt to rank kickboxing heavyweights across eras runs into a problem that most attempts simply ignore.
Rico Verhoeven held the GLORY heavyweight title for more than a decade, which nobody in the K-1 era came close to doing. That is a real achievement, achieved under a ruleset that punishes resting: GLORY breaks the clinch immediately and penalises passivity, so a heavyweight cannot lean, tie up and recover. Verhoeven built a game around outlasting opponents whose power exceeds his, and against Badr Hari — twice — it worked exactly as designed.
At the same time, the heavyweight talent pool contracted sharply after K-1's collapse, with a large share of the physical specimens who would once have become kickboxers going into mixed martial arts instead. The field Verhoeven dominated is not the field Hoost, Aerts, Schilt and Le Banner had to work through, and pretending otherwise is not generous to him — it is just inaccurate.
The ruleset point cuts both ways too. Under a code that permitted resting in the clinch, several of Verhoeven's wins would have been closer. Under GLORY's passivity rule, some of the K-1 era's slower heavyweight fights would have drawn warnings.
The conclusion is unsatisfying and correct: cross-era rankings are comparisons between different sports wearing the same name, and the useful question is not who wins but what each era's rules were selecting for.