Paranormal Romance. It seems that all the books out there for young adults are paranormal romance. And dystopia starting to pick up as well. Like the Hunger Games and the City of Ember. But you should write what you enjoy writing. Just because paranormal is big right now doesn't mean that it will be in two years, or even the next year. And Twilight started the vampire frenzy, which I believe is now slowly dying out. I think zombies are the upcoming thing now.
Anyway, write what you're best at. People will gravitate towards it no matter what the popular genre is.
P.S. I suggest romance. If you're looking for profit, they seem to sell the most.