Texas Vs. Missouri
Without knowing the exact nature of the business you would be conducting, it's hard to answer that directly.
Typically, the business would need to be registered in the state where the physical business would be located, such as if you have an office, property owned by the company, employees, or if the business is physically conducted in person.
If the business would have nexus in various states, such as Texas and Missouri, you would most likely need to register the business in one state and then file as a Foreign Entity in the other state(s) of business. If that is the case, I would suggest registering your LLC in Texas first, as their foreign entity registration fee is very high compared to Missouri.