Hi fellow Texan applicant! Seems like Long might be the right first choice for you because you sensed students were happy, won't have to deal with Houston's grid-issues, and volunteering/research in San Antonio is not as competitive as in the TMC where there are a zillion med students. Also, San Antonio is a big city that has a lot going on & you can guarantee you won't be in Temple lol
I think fellow student stress is something you gotta reflect on. If you know you are pursuing a less-competitive specialty, are you okay with letting the gunners be gunners and finding your own peace? Are you someone where if your friends are stressed, you pick up the vibe/mood they have?
I think if hapiness of students is your first criteria, maybe Long > Baylor > McGovern > UTSW. But if you feel you can find ways to be happy even when peers are miserable, consider Long > UTSW > McGovern > Baylor.
I've not actually gone to medical school yet so take it all with a grain of salt. Best of luck on your journey!