Wanted to reference a point I made on the old thread for this page here: https://www.flyertalk.com/forum/brit...ounced-17.html

When booking an AA flight on BA.com, it appears to allow you the extra baggage and seat selection (if Silver or above). So in essence, if you're booking one of these and have the option of BA or AA, the latter will give you both, whereas BA won't give you checked baggage. The chart above is incorrect in my experience when doing this as you do get free seat selection on AA that includes Main Cabin Extra, even exit rows which BA as a Silver would make me pay for. And when the product offerings are very similar, it's definitely worth thinking about AA > BA.

The important point about this is that BA still sells the Basic economy or regular economy option on the website for an AA flight. So needing a bag for this trip in November, I selected regular economy on American at an £80+ (£40 ew) uplift not knowing these benefits. As it doesn't state these when you book there's no way to know, so I phoned back refunded the flight and booked the basic economy fare instead saving me £80, which is a very good saving when you're considering booking one of these in the first place.