When it comes to deciding what type of class you need to get certified at or teach don’t focus on present trends. Trends always change. You need to find out what is it that you like to teach and then your choices become more clear. And most important, you need to be able to train a clients in a way that is most appropriate for them so they can reach their goals.
Just because someone says, “this method or trend is the most popular” it doesn’t mean that it will stay that way. Christine is correct when she said “In terms of what you teach, it should also be something that you have a desire or passion to teach”.
The best thing to do, is to keep educating yourself as much as you can and maybe specialize in one or two different philosophies. Good luck to you!