If you value simplicity, I would just focus on cash back and get out of the Amex ecosystem. It’s pretty impossible to put all expenses onto Amex IME because there are still places that won’t accept it (especially small shops and places internationally).

The BoA Premium Rewards card becomes a very powerful 1 card system after you transfer some investments over to the firm and join the preferred rewards system. After that, you’ll earn 3.5% back on dining and travel along with 2.625% back on everything else. It has no FTF. For the $95 AF, you get a $100 airline incidental credit and a TSA Precheck/Global Entry credit (which is actually helpful if you truly want a 1 card system).

I can’t think of a better 1 card system out there. If you are set on having a 1 card Amex MR system, it really comes down to Gold vs. BBL imo. If the gold credits work for you, I think it usually comes out on top.