Should I credit my Melbourne -> Santiago return flight on Qantas & LATAM to Qantas Frequent Flyer or AAdvantage?

I am flying to Santiago from Melbourne round trip on Qantas and Latam (discounted economy). Should I use my Qantas frequent flyer number or my AAdvantage to maximise my earning potential?

That probably depends on the fare class (this is a single letter, such as B, Q, or X) you have booked this flight in. If you can find that then I’d suggest using wheretocredit.com and seeing which programs you are interested in might earn you the most points.