If you are passionate about writing and would like to make some money with it, then you might want to consider romance as the genre to go with. Romance is consistently a bestseller and the genre rakes in a billion dollars a year. Other genres and subgenres may come and go, but romance always does well. 

A few years ago, you may remember the phenomenon that was Fifty Shades of Grey. After its release there were thousands of similar books flooding the market because sex sells. As does sweet romance, if you prefer. You may think that the market is oversaturated with romance books, since it is so popular, and you are not wrong, but there are many tropes and situations which will grab readers, and romance readers are loyal. If you write a series, there is a good chance that readers will snatch up the whole series to find out what happens. I would recommend releasing books in a series in quick succession, so they don't lose interest with a long waiting time.

If you go to Google analytics and research the popular genres on sites such as Amazon, you will be able to see what is hot right now. It can change quickly though, so if you want to get a similar book out there then you'd better be fast. 

Make sure you have a quality cover and a great blurb to go with your book and do consider Kindle Unlimited as an option as readers will devour your pages if it appeals to them. Longer books will earn you the most on page reads, but a series of novellas can do just as well. Do research on 'popular series' and see how they are marketed to readers.

Romance appeals to a lot of readers because it offers them hope, escapism, and romance that they may be missing in their lives. Romance is easier to immerse yourself in than fantasy as it is easier to believe it can happen to you. There are many subgenres to consider, but contemporary and erotica are the top sellers. If you have issues with writing erotica, and it is not for everyone, then you might consider sweet romance. Look at the likes of Hallmark. Every year they release multiple movies with a similar storyline and people binge on them religiously. Sweet romance is always a happily ever after situation and despite the almost identical storylines, people do enjoy knowing that everything will work out in the end.

If you are new to the genre or new to writing in general, please do your research and read as many romance books as possible so you are up to speed on what readers are looking for. You need to understand the tropes and how they should play out. It is okay to try something new with your stories, but don't stray too far from what makes them work or you may lose your audience. Romance can be a profitable genre to write in if done right.