If you qualify for a subsidy
HealthCare.gov is the most affordable coverage available, full stop. Medicaid is not expanded in Texas.
If you don't
Full-price marketplace plans are the most expensive coverage in Texas. For healthy people, private PPOs on Cigna, Aetna and PHCS PPO are routinely 30–50% less. Texas has no state individual mandate and no state penalty for going without coverage.
What's not affordable
Health-sharing ministries and indemnity plans look cheap until you have a claim. Ask for the out-of-pocket maximum; if there isn't one, it isn't insurance.
Texas has the highest uninsured rate in the country, and because Medicaid wasn't expanded, adults under the poverty line fall into a coverage gap with no subsidy at all.