Never Been to Austin
If you are only visiting Austin temporarily and have just a few dinners (or one?) to tour Austin cuisine, I honestly wouldn't recommend any one of those restaurants you mentioned - not because any of those restaurants are "bad" by any means, but rather because I think there are other restaurants in Austin that more fully embody the "essence of Austin" I suppose.
How many dinners/lunches will you have in Austin? I think most people's food recommendations will strongly be influenced by your answer to this question.