I am from Southest Houston and decided to go to Dallas for College. Although I am biased towards my city (just like everybody else is:), I have grown quite fond of Big D. As a person that has lived in both places, don't think that Dallas is just a big town like some people percieve it to be on here. It is a major metropolitan city with a great metro area (very similar to Houston, except Dallas has steroid suburbs).
I do like the laid back attitudes of Houstonians, but that's what makes the two cities different. Texas would be boring with one bland attitude.