AA has had coupons over 30% in the past. I've used multiple in the 2015-2016 timeframe. ASAIK they had very few use limitations.
Recently, AA has been far less generous with their coupon offerings. Some of their coupon codes have limitations (as in a min purchase). Yesterday I loaded up my cart with a few items and tried to use the HXJ6BX code but was shot down because my order did not meet the minimum $$$ threshold (I was under the assumption the code had no minimum).
I've been using AA for over 30 years, mostly because I have one only 1.5 miles from home. If you need something quick ... AA may be the right choice. If you can plan your project ahead of time places like Rockauto are superior in price.