Crocop. Schilt had a his MMA career before his K1 achievements, he is one of the all time greats in K1, but not in MMA. I love Hunt but he is 9-8 in MMA.
you mean in MMA right? he has like 80 fights in K1
Overeem ain't a K-1 fighter. Overeem is originally a MMA-fighter (2H2H, Strikeforce) who accidentaly won the K-1 WGP. Overeem started his career as a MMA-fighter which he kept on doing with some short visits in K-1 Japan. Schilt's MMA-career was really gone in a split second when he adapted himself in kb.. Crocop established himself as a decent MMA-fighter with a decent K-1 career as well. But just looking at the fighters you mentioned, Schilt's palmares is the most impressive and he is for sure the greatest fighter of all 6.
Cro Cop. But I think Semmy has an underrated MMA-career. Around 2000 he was a top five guy and after establishing himself he only lost to the best of the bests. Knowing what he matured to in kickboxing (best HW ever), I think he would have had great future prospects in MMA.
Overeem was an MMA fighter first, that's an odd pick.
Semmy would have had a hard time being as effective as he was if he had to stay under 265. But remember falling for those rumours that he was coming back to the UFC 4 years ago. I though that would have been awesome.