I usually write Erotica, have been since middle school. These last three years I've been out my comfort zone and doing Action/Adventure.
I like SF, Historical War/Adventure (anything from Rome to Edwardian England), Horror, Modern Adventure, and of course Erotica. However my works often overlap. I have done or am doing SF Erotica, SF/Horror, Erotica and all the others. Why? Well, I am a great military SF fan, but I also like Historical Warfare a lot, with a great love for SM Erotica (non-romantic). I added the qualifier because many people seem to find Romance to be integral with Erotica. I do not.
I love horror and all things scary so that's what I usually lean towards when writing. Even if I set out to try t write something else I find my mind slipping back to the spooking things I love. I do believe that a writer should stick to what they know but I would also like to expand my ability to write on a variety of themes just to improve my writing in general. With all that being said, the thought of me writing anything but horror is in it's self scary
I was going to say I like writing romance because that's what I can sell, but I actually think I like it for more reasons than that. It's just such a broad genre - I can write SF/F, historical, contemporary... lots of room for variety. I like that!
I choose the plot and theme, but not the genre, it just kind of imposes itself, and most of the time it will either be romance/paranormal/magical/historical YA, paranormal/romance, or dark mystery
I like writing young adult, mostly paranormal or science fiction. Everything I write has a certain grittiness to it though, that i couldn't see writing without.
Horror: To show that people aren't what they seem and to scare/creep people out. Science Fiction: For the same reason as Horror as well as all the spacey stuff.