You could make your decision a few ways;
- You can write what you love and are passionate about. You will have a deeper understanding of the genre this way.
- You can make a pros and cons list of the genre or genres. This will tell you if you can be bothered writing it or not. But remember, that anyone who can be discouraged from writing, should be, because they just don’t want it bad enough and they aren’t passionate enough.
- You can go with your gut. Forget what your friends and family tell you, forget the marketing, just think about what you know and love.
- You can pick the most marketable genre. This could be tricky though, as you have no idea where the market is going.
In the end, it is up to you to choose the genre you write. No one can choose for you.