Smart way to access an LLM?

I’d like to use an AI service to go through my novel and point out areas of over-explanation, and maybe similar subtle issues.  Am I likely to get better results from a paid version over my current use of the free LLMs, which are not great at this, nor is ProfWritingAid. And what are the pros and cons of going directly to an LLM site like Claude and taking out a subscription for a month, or using something like Novelcrafter to access such a service?