Definetely AA/BA.
Iberia is overall a bad airline, not good customer service.
If you are going on coach. Try AA all the way. BA is ok but seats in coach suck, AA has more room and makes a whole lot of difference.
I just took 2 rt to lima in the last month.
AA service in coach is bearable, well bring your own drinks, last rt was pay for your drinks
If you can take LanCHile I would do that, same as AA but will go LC over BA.