Sorry to necro this post, but I think it could lead to an interesting discussion.
Ink by Inkle Studios has the best markup language I’ve seen so far for creating branching narratives. It’s human-friendly and has a clear nested hierarchy that lets you visualize your branches. It has integration with Unity and it’s so flexible. It shines when used as middleware, where a non-technical writer can focus on writing the interactions and export them as json files so they can be integrated into an engine.
But I’ve decided to use Narrat instead because it’s a “complete” engine with support for things I knew I wanted like multiple audio channels, screens with clickable elements, dice rolls, and skillchecks. It’s more of an out-of-the-box solution in my opinion. So here I am!