Captain all the way! Specially captain on 320 where you'll be able to get a new job easily if anything goes wrong. Qr is a great company for DEC or FOs looking for command upgrade. Sure QR has a MUCH better package than AA, but I think it is too risky to join QR as a FO counting you will get upgraded, that might never come if you get involve on any of the many situations where you can get a caution letter for example, specially if you join o 320 fleet where it is more likely for things to go wrong. And finally, you will for sure enjoy way more your job sitting on the left than on the right.... To me is a no brain situation, but good luck!