Originally Posted by
DownUnderFlyer
CX might be easier when flying in the back. I would not go for BA unless you really fly BA a lot.
Only for AA, really. CX is much more restrictive for Y on other carriers (even on CX itself).
And actually there is a "loophole" to earning miles on O-fares on AA as well. If you get upgraded from O, then you also get 100%. So, with some advance planning, you can usually get full credit from AA on CX for any paid fare.
But CX is not good if the OP plans on flying BA/QF in deep discount Y. Though, that's a losing battle in any OW program, really.