Suspense and romance are always hot. If you're trying to start writing for the hottest genre of the moment, it's good to keep in mind that by the time you finish the book, get an agent and go through the whole publishing process, the market might be already saturated and looking for something different. Besides, you'll always be overshadowed by that one great book that started he trend and it may even be easier to get rejected just because your book turned out a bit too similar to it.