I flew PY/PE from DFW to SYD 2 years ago in the exit row. Great soft product and nice (not amazing seats). Flew AA back to LAX in J which was way nicer in the seat department (used a SWU).
1) Being a OW Emerald, you would have access to Qantas F lounge in LAX. That's an amazing lounge
2) J on the AA flight beats J on Qantas any day
But if upgrades are tough on that LAX flight now I would take the direct from DFW and maybe you will get to bid for J. I got the chance (and did not bid enough!)