This is my opinion:

NA-Europe

1. BA, Great seats, good food, great drinks and some of the best lounges.

NA-Asia

SQ or CX. Great service on both. If flying through HKG then CX for the lounge.

Europe-Asia

Tough

SQ,CX for the reasons above or BA just because I have grone to like their service style and I am British. But If I was being rational about it SQ.

No doubt you will see a lot of different answers to you question as it is all down to taste and what you have gotten used to.