We chose LangGraph to build our coding agent 1 year ago
I think the main thing LangGraph adds is a state machine framework for human in the loop with time travel.
So if you have an authoring workflow where a doc goes through a bunch of steps, and at some steps the analyst might want to fix some LLM output manually, and try a couple of things and then go back to the way it was before and try again, it will do that and you won't have to make your own state machine.