For me, it's:

Fiction Writing With AI by Nicolas Cole.

Never fails to disappoint.

It gives access to great ChatGPT prompts.

It helped me understand what AI are great (help crash test a plot structure for example) at and what humans or better at right now (like writing prose).

I got a new prompt to develop my Fantasy writing every week.

The very last one helps writing loglines (headlines for stories).

Go try yourself! You won't regret: https://fictionwritingwithai.substack.com/