First off I am a little confused have you completed 1L or have you been accepted as a transfer student to those schools one semester in? It just seems odd that any school would accept a transfer before 1L was complete, but if they did good for you.
With that said I know many people that transferred from my school and were miserable and others loved it so it is a highly personal decision. I think this are some factors to consider.
SMU is in Dallas and Tulane in New Orleans and STCL is in Houston as I am sure you are well aware. Now one thing many of my friends that transferred didn't consider was the reality of being in a new city for law school in an environment where they didn't know anybody. I know nothing about your life, but if you were born & raised in Houston have family, friends, and a whole support group there leaving that may be tough. Particularly when you attend a new school where all the 1L clicks have formed.
However, if you have a personality that is really outgoing or you simply don't really care about friends etc then it may not matter. Also make sure those are cities you want to live in when you graduate. Odds are you will develop a lot of connections at whatever school you attend for the next 3 years and where your internships etc will be. If you do not want to live in New Orleans then going to Tulane might be a bad idea. If your gf lives in New Orleans, your a huge Saint's Fan, and your uncle has a huge law firm in New Orleans you could work in it would stupid not to go.
Point being is really think about the city you will be living in and how you will manage in it this will have a huge impact on your law school career. COST
STCL is 26k compared to Tulane at 42k & SMU at 40k. I imagine if your in the top 2% you can get a solid scholarship offer from STCL not to transfer and possibly save yourself 70-80k accruing interest. If you attend SMU or Tulane you will paying 14-16k more in sticker a year assuming STCL doesn't give you a scholarship. Over two years that is 28-32k accruing interest at an 8% clip. If STCL gives you a 20k scholarship then you would pay 12k in tuition over the next two years opposed to 84k or 80k at SMU. I am a lawyer now and I can tell you the loans are no joke and the interest accruing on it is awful minimize it the best you can. PERSONAL FEELING ABOUT THE SCHOOLS
I think this is extremely important it sounds like you are performing extremely well at STCL and if you have friends, connections with professors, etc then it may not be worth leaving. I went to STCL for a mock trial competition and really liked the feel of the school, but that was my personal opinion. If you hate it there and want to get out then you should do it.
However, I would recommend visiting Baylor and SMU from my experiences visiting various schools during mock trials I noticed that each school has their own vibe/culture to it. Some of the schools I loved others I hated and that is my own personal feeling. So if your going to transfer to either of these schools visit them interact with students, talk to professors, see how you feel there because once you transfer there is no going back. RANKINGS
I'm in California and I honestly don't know what any of these schools are ranked, but I can tell you in the real world law school rankings mean very little unless it your at Harvard, Yale, etc and even then it doesn't mean a whole hell of a lot. Go into a real courtroom and see how often the attorneys mention what school they attended in a murder trial, or multi-million dollar lawsuit. I have yet to see it happen, but maybe one day it will.
Also remember U.S. News is a for-profit unregulated magazine offering an opinion and you shouldn't make a life altering choice based on it alone. U.S. News ranks more than law schools as well according to them Albuquerque, NM is the best place to live right now and South Dakota will be the best place in 2032. I am not making this up either here are the links. I personally am not going to move to Albuquerque which is #1 or Auburn, Alabama which is #2 because U.S. News says so. I am sure there are some legitimate reasons for the cities ranks, but I am not going to make a life altering move based on what a magazine says I suggest you use the same logic when deciding whether to transfer. http://money.usnews.com/money/personal-finance/slideshows/best-places-to-livehttp://money.usnews.com/money/retirement/slideshows/best-us-regions-to-live-in-2032/3