The fact that I have all the computation described in a coherent manner, in something that's agnostic to the language I'm using.

The same description (the graph) can be taken and used in every other language. I can move a trained model to production just picking a single file (a `tf.train.SavedModel` IIRC), give it a tag and I'm ready to go, with different models with a native support for the "tagging" (hence the model versioning).