My first story ever, Let's Imagine a Female Knight, was a contest story that came from my childhood dream of having a badass female knight journey the world and slay monsters. It's a dark fantasy and includes lots of controversial topics and many gory scenes, but grimdark anime/LNs holds a special place in my heart so I'm glad I could complete it in about a year's time.
I don't know if I like it the most (as I'm currently writing two ongoing novels), but I honestly had a lot of fun writing the fight scenes and thinking of ideas for weapons and monsters. It allowed me to take a look back and look at things that worked and didn't work, especially when you're trying to invoke feelings such as dread and fear in my genre of expertise, psychological horrors.