I've been hashi's/hypo for 25 years now. My thyroid is 100% non functional.
I take 90MG Armour and 75mcg Synthroid. I did not do well on each individual drug. Others report good results using only Armour. I never felt well on Armour alone.
Another thing that helps. I chew up the Armour completely. Then drink a full glass of water. Rinsing the Armour from my teeth and swallowing it. For some reason, I absorb it better this way.
There was some talk about Armour containing more T3 than is normal and less "T4" than is normal for humans. Hence my combination. It works quite well for me.