And Stu pointed out above that the best seat on the UA plane isn't as good as the worst seat on the AZ flight. I've never flown AZ but did the E+ on UA SFO-SYD in March and it was no hell. My friend raved about her economy seat when she went from LAX-AKL-MEL in May. So sounds like you may be better off on the NZ flight.
I do find it surprising that SE's don't have special status, though.