I have/am using Scrivener, Obsidian, and Ulysses for writing. Unless one wants to mess with CSS I’m not sure Obsidian is the best choice for scripts and book writing. For long from writing I find Scrivener’s scrivenings feature, or Ulysses’s glue feature, to be indispensable to temporarily combine multiple documents/sheets to get a better sense of the flow and transitions of the text. I may be missing it but I have not found a plug-in that replicates the scrivenings or glue features.
That said, I’m not an expert yet with Obsidian but here is where I’ve landed:
- Obsidian for all research notes
- Ulysses for writing
I would love to do all research and writing in Obsidian so if anyone can correct my understanding and point me to a plug-in that can replicate the scrivenings or glue features I’d be grateful! 
PS, I found this post on this forum related to this. Document Spanning