Originally the Big 8 was just going to add Texas and Texas A&M, but Texas politics got involved and forced us to take Texas Tech and Baylor. Those two were probably the most deserving. You could make an argument for Houston over Baylor, but all the major conferences have a private school so I guess the Big 12 should have one too. Besides, I believe Houston's program was starting to slip a bit, and Baylor has a bigger stadium.
I've got nothing against Texas Tech or Baylor, but I think it would have been better for the North schools if the Big 8 had been able to add just Texas and Texas A&M. By taking in half of the SWC and making one-third of the conference Texas schools, it became more like a merger than Big 8 expansion. The South schools gained power, the league offices moved south, etc.
The Big 8 plus Texas and Texas A&M would have all the same media markets the Big 12 currently has. There would be no divisions and no championship game, so it wouldn't be about the strong South and the weak North. Teams would have a nine game schedule where you play everybody every year. In basketball you could play everybody home and away.