If you're looking for another NovelAI alternative, StoryNest.ai is worth a try. The AI-powered service for storytellers has a variety of tools to help you write a compelling story, novel or interactive narrative. It includes character generation, world-building, AI editing assistance and voice narration. It's adaptable to different writing styles, and you can sign up for a free account to try it out.
Another service worth a look is AI Story Generator. The service uses natural language processing technology to generate new stories based on prompts you enter. It can be useful for breaking through writer's block and exploring different styles and genres. It's geared for high-volume content generation and has a simple interface that's easy for writers to use regardless of their skill level.
If you want a full-featured writing environment, check out Novelcrafter. The service has a personal Wiki for storing story details, multiple writing modes and AI tools to help you along the way. Novelcrafter can accommodate both planners and pantsers with customizable tags and labels, and you can set AI context and prompt settings. It's available in several pricing levels depending on your needs.
Last, Sudowrite is an AI writing assistant for fiction authors designed to help you get past writer's block and finish your book. It's got tools for idea generation, outlining, writing and editing, and it can handle different parts of the writing process. Sudowrite comes in three pricing levels, including a free trial, so it's a good option if you want to try out an AI writing assistant.