First, congratulations to you on your multiple acceptances! That's a great problem to have. You are 100% correct that UTSW and BCM are the "premier" programs in the state. I would even consider UTH higher on your list if you were considering pediatrics so you could go through Texas Children's. I think BCM has more time off and has the best boards in state vs nation?? I remember hearing their average last year was high 240s. On the otherhand, UTSW has largely the best ranked in-state residency programs with a few exceptions where you could use your training as a springboard for that.
If I were you, I would try and find a copy of all match lists from previous years and see if it has people going where you want to go. It seems like you probably crushed undergrad/exams.. I think you will have great opportunities no matter where you go. If you went to a lower tier on your list, you are correct that there may be some bias favoring the better regional programs. But if you crush step, you're getting invite to interview for residency way more times than not. Admittedly, this does not hold true for brand name programs that like pedigree like PENN.
All that being said. The short answer is I don't think it matters after step 1. I strongly feel that school rankings matter insignificantly at the level of the individual. I go to a lower tier Texas school, have high scores, and have invites at top programs in a competitive specialty. Go where you'll be most happy. The next four years will suck sometimes.
Let me know if you have any questions.