One project I’d add to the comparison is raghilda from Posit:

https://posit-dev.github.io/raghilda/

raghilda is deliberately narrower than LangGraph/Haystack/etc. It focuses on the RAG parts: document ingestion, chunking, embedding, storage, and retrieval. It’s meant to leave the pieces visible and replaceable rather than wrap the whole application in a framework.

It also composes well with the other parts of the Posit ecosystem: chatlas for LLM interaction, and Shiny for building interactive apps around the result.

My bias is that orchestration is often better hand-rolled for the specific application. Once the framework gets too far removed from the actual steps, it tends to bring in a lot of complexity you probably don’t need. In the end, most of these pieces are not that complicated.

Disclosure: I’m one of the authors of raghilda.