Cro Cop, even though his right arm doesnt come up to defend his face when he does it!

No one survives it anyway so its a moot point.
Cro Cop was not the best overallin K-1, but he did have the best high kick. He aims it perfectly, times it perfectly and throws it with ridiculous force. Its unreal. Aerts is good, but Cro Cop's kick wins it.
Other notable kickers in K-1
Buakaw; the living embodiment of Muay Thai
Jerome Le Banner; Amazing mid roundhouse kick, but only throws it when his opponent is stooping, watch a JLB HL and you will see him using this to devastating effect
Remy Bonjasky; loves flying around the ring with Khao Loys (flying knees) but they rarely hit (when they do they are devastating though) but when he uses his normal kicks they are ace too.
Hoost; Great low kicks, devastating to his opponents thighs. Trashed Vovchanchyn using them, and Igor is a harded kick boxer, but he couldnt handle the onslaught!
MOST OVERRATED KICKER IN K-1...
GLAUBE FEITOSA!
Yes, his overturning kicks look amazing (Im learning the Muay Thai equivilant myself atm, same kick different name), but it only works if his opponent is turtling (standing still defending) or moving back. When people figured out that by closing the distance, Glaube had nothing to combat them with, he started to look a little exposed. His kicks also arent all that powerful. He lands really clean, but the nature of the kick, hitting the deltoids and neck, rather than the cranium (which would break the kickers foot) means it doesnt KO people.
Looks great, but not actually that good a kick.