This is a hard one. There's Don Wilson, Bill Wallace, Benny Urquidez, and more modern fighters like Peter Aerts, Ernesto Hoost. I've went for Smith, but I'm torn. Alexis was tip top too, but Don Wilson proved himself a lot.
Heavyweights: 1) Maurice Smith 2) Tony Palmore 3) Joe Lewis Neither Cikatic nor Alexio were heavyweights before K-1. They just jumped on the heavyweight train for K-1 and ate up.