Yeah Kiba seems to have the toughest opponent. I was always hoping Neji would end up fighting Sakon for this very reason...
As for Naruto vs Kimimaro. There really is a 50-50 chance of either one winning. Perhaps next chapter Kimimaro will immediatelly activate the Gaia seal on his chest and go Level 2. Then we will have an idea about what kind of power that thing has.