There are dozens of AI writing tools now, and no single one is best at everything. Here is the honest short-list, grouped by the job each tool is genuinely good at, so you can build a stack instead of paying for overlap.
For full book generation: BookForge AI
End-to-end pipeline from a one-sentence idea to a KDP-ready EPUB with cover and audiobook narration. Real-time streaming chapter generation using Claude Sonnet 4.6. Generous free plan.
For prose polishing: Sudowrite
A beloved sidekick for line-level craft: rewrite this paragraph tighter, expand this description, brainstorm names. Not built to generate a whole book — but excellent inside a manuscript you’re already writing.
For organization: Scrivener or NovelCrafter
Scrivener has been the pro author’s manuscript tool for two decades. NovelCrafter is the modern take: story bible, codex, plug-in AI, low monthly fee. Neither generates covers, audio, or export files.
For research: Perplexity + ChatGPT
Perplexity for cited fact-finding, ChatGPT for open-ended brainstorming. Do not use either for actual book generation — they lose context over long documents and produce generic tone.
For covers and illustrations: Nano Banana or Midjourney
Nano Banana (integrated inside BookForge) is faster and cheaper. Midjourney still has an edge for very stylised, painterly work. Pick one, stop paying for both.
The honest stack
A working 2026 stack for most authors: BookForge AI ($19–$39/mo) for generation, cover and export; Sudowrite ($19/mo) for line polishing on manuscripts you’ve already generated; that’s it. Everything else is a nice-to-have.