I don't know about the other two, but Austin is a fantastic city. It has great weather--300 days of sun--it is a bit hot for some, though no more so than your other choices. It has a great mix of things. State government is there, nice city parks, major university, nice downtown with restaurants and live music, lots of different festivals come through there, and not to far away is the hill country and a sizable lake if you like beaches and boating. While it is a good-sized city it never really felt too big to me. Of course with any city, the exact spot you pick within it makes a huge difference. I lucked out and ended up getting an apartment that was pretty ideal.