I do love spookier/horror elements. Give me your ghosts, shadows, unexplainable phenomenon. Think THE WHISPERING DARK or WILDER GIRLS vibes.
I'm not against monster-hunter/vampire-slayer type stories, but I often tend not to be right for them.
I am pretty picky with my YA spec fic interests, and it's sort of an "I'll know it when I see it" situation. That being said, I tend toward contemporary fantasy, horror, and/or relatively grounded narratives that feature some kind of speculative twist (i.e.: CEMETERY BOYS).