Quick Answer
AI can help write a novel but cannot produce a publishable one entirely on its own yet.
Detailed Answer
AI struggles with the core challenges of novel writing: maintaining character consistency across chapters, developing themes, and creating a unique authorial voice over 80,000+ words. Claude is the best for prose quality and can write compelling individual scenes. The most successful approach is using AI as a brainstorming partner, outline generator, and first-draft assistant while the human author provides vision, voice, and editorial judgment.
Find Your Own Answer
The best way to decide is to try them yourself. Council lets you compare multiple AI responses to the same question.