If hctz (hydrochlorothiazide) doesn't work to lower BP what would be the next med?

Depends. On who we are and what other medical conditions we might have. Some meds work better in certain ethnic groups. Other meds are picked if you have heart disease or diabetes. Talk with your doc about the best choices for you.
Many options. There are many options to treat hypertension that can be tailored to each individual patients needs, medical history. Commonly, there are meds called calcium channel blockers, ace inhibitors, angiotensin receptor blockers, beta blockers and more.