Live in Austin, raised near Dallas, have buddies living in midtown Houston area.
For the younger crowd? Austin. It's not even close. The atmosphere, events, amount of parks/outdoor entertainment that are free.
I disagree with Woody, it's incredibly diverse, in my opinion. Hell, half the people that live in Austin aren't even from TX at this point. California and NE area are the prime imports, but there's really an incredible amount of transplants here.
If you're in business, then Austin is probably going to be a completely different experience from the NY financial industry. Most of the companies here that are worth anything have adopted the Google/new age type workplace. If you're in finance, you'll probably still have to rock the suit/tie but companies here are really embracing their employees. If you can find a job in tech with your finance degree, you'll be made in the shade. Austin has grown into an IT powerhouse. And they pay.
I don't like Houston. It's a "professional" city. By comparison, Austin is completely laid back. If you live anywhere downtown in Houston, it's dirty. Every single time i pumped gas in midtown I had people asking me for money. I didn't get to drive in rush hour traffic, but I heard it's terrible. On that note, Austin is very bad too. Austin is more likely to give you a flex work schedule though.
Dallas is so spread out at this point, it's really going to be completely dependent on where you're working/living. Some burbs in Dallas are pretty cool, DFW has grown into a nice area, and some of them are "family" areas where you're going to be bored a lot.
Austin -> Dallas -> Houston is my pick. I don't really like Houston at all. Austin is probably the most expensive though so keep that in mind. It's either the fastest, or one of the fastest appreciating markets in the country right now, thanks largely to the tech industry. If you don't want to live in the hood or in a 30 year old apartment, expect to pay at least 1300 month in bills for a 1bdrm if you want to live anywhere within a 10-20min drive to DT area, and that's basically for a roof. There's a lot to do though, so as long as you don't go too far out, you'll have stuff to do.
And the food trucks. Oh lawd.