I prefer Shiki over Shirou. He is just a guy trying to survive. He helps Arcueid and does his heroic task but he doesn't do it for some childish notion of being a hero.
He is just a guy trying to live his nornal life, spending time with his bro Arihiko, trying to reconcile with his sister Akiha and trying to get chicks but he is forced to do heroic tasks always lying on the border of insanity.
Unfortunately for him he is destined to have an even shorter life than Shirou.