From both schools, which one has the better math program?
Not focused on math program specifically, but here is a lot of information comparing the two universities.
Which one has better math program? Depends on who you talk to. And which forum you post in!
My opinion? All the stats in the above link are more important factors in your decision than the math programs.
Apply to both.
If you care about US News rankings, UT’s grad program is ranked 14 and A&M is ranked 41. Undergrad may not be the same as grad school.
Rankings are all subject to methodology biases. As a future math major, you probably know that.
Merit aid is generally better at A&M if money is an issue for you.