All four have the same format, and seem to use the same template. I just joined VASIA, and I like it so far. It is very flexible, and I biased for SQ (I used to live in Singapore). I checked out CX, and they have a big advantage. They have a Oneworld Alliance, which allow you to fly flights for the other airlines. That way, if you feel like flying an MD80 to DFW, you can with the airline. (Sometimes I feel like doing shorthauls).