I think Haku is more skilled in using Ice Release than Kimimaro is with his bones, Shikotsuiyami or some random name, but overall Ice Release is still better I think. I like Elemental KG more than normal KG anyway so yeah
based on what we see, without a any training haku was able to destroy homes and kill with ease wile kimmaro just had good tai......so i was to just be a random member of a clan then hakus but if i was to be a master of the kg then kimmaros
I think it depends more on the skill user....in s fight between the two the Ice style user could avoid the Bone release user, but probably couldn't damage them....though they could possibly freeze them....
I honestly love Hyouton (Ice Style) so that's what I'll go with