Based on my understanding, the Chicago school that people like Friedman are a part of, and the public choice folks like Buchanan are more 'free market' than the others.
But their utilitarian positions could end up with a situation where the state favours big corps, making it easy for socialists to get people on their side by saying, 'See? We told you so!'.
They also seem a bit muddled and inconsistent, to the point of making no sense in practice, which they deflect from with fancy numbers and appeals to empirical analysis.
Austro-libertarianism on the other hand tend to be steadfast and consistent. Its methodology itself is different. It's a well-developed intellectual body and neither 'left' nor 'right', so they seem to favour and criticise both sides, since its a separate school of thought of its own. I have no idea why these ideas are irrelevant when they just make complete sense. I consider myself to be in this camp. And it seems to me that Bitcoin will definitely spur these ideas onto the mainstream in the coming years. I'm feeling optimistic about it.