There isn't going to be an answer for "best/hottest" kind of question. And frankly nobody knows the answer. If the answer is obvious, people would be all over the subject.
Timing for the next best thing has proved to be a fruitless pursuit. My only advice is to hone your technical skills, learn a new language, read new books, meet new people. You have better chance of being at the right place, right time doing that.