what is the right medicine for you to treat thyriod problems

My experience has been to actually try different thyroid medicines to find which one makes me feel the best. I do not really know the reason why there is such a difference (GP once told me they had different hormones) but know that there is a huge difference.
As far as least side effects...ask your doctor, pharmacist, or do research on each medicine to find out what their listed side effects are.