I have to say Zero. For some reasons, the more I look at Kaname, the less hotter he is. But when I look at Zero, he gets a lot hotter. o.O That's the weird part for me, but I will choose Zero instead of Kanama.
Zero and Kaname share the same hotness, for a fictional character. Kaname has beautiful brown hair with luscious eyes and a caring, gentle personality. Zero has the bad boy look going there with his scruffy hair and solemn eyes. He is pretty solemn, ignorant,mildly-tempered... You get the point. But beneath that all, he is caring.