The way I see it, one cannot make a rational decision about AIs or Tamoxifen without knowing one's risk of recurrence. If you have a tumor with very low risk of recurrence, you might want to try AI or T, and stop if you have bad side effects. But if your personal risk of recurrence is high, you might be willing to put up with even very bad side effects, rather than face a high risk of recurrence or an early death. One measure of risk of recurrence is the Oncotype test. Medical oncologist can order it--make sure you get it--or whatever test s/he recommends to assess risk. These tests (e.g. Oncotype) test the tumor's DNA (not of your DNA).

My personal risk of recurrence is 18%. I take both exemestane and Kisqali. Luckily, I have very few side effects from either. BTW, 70% of women who take AIs have few or no side effects. But 30% of us are unlucky. It would be great if we knew why!