If you want to improve your creative writing skills and create engaging stories, AuthorGPT is a good option. The AI tool can generate full-length books in a range of genres, from Fantasy to Romance, and lets you set settings and characters, making it a good choice for creative people who want to try their hand at novel writing or aspiring novelists.
StoryNest.ai is also an option. The service offers AI tools to create stories, novels and interactive stories. With character creation tools, world-building, AI-assisted editing and collaborative editing, it's geared for writers in several formats including interactive fiction, novels and screenplays.
Last is NovelAI, a subscription service that uses AI for storytelling and virtual companions. It includes tools like the ability to generate images for character visualization, a text adventure module, a customizable editor and tools to write in different styles. That means it's a good option for writers who want to maintain their own voice and style while still creating engaging stories.