It really depends on who you are going to use for award flights, and the percentage of Y that you will be flying.

AA will give more credit for cattle car that BA or CX, which is a help in making PLT. AA does require 4 (I think) paying segments a year for an "overseas address".

BA goes on class and the length of a flight to determine how many points you get or making silver. Take a good look at their website and calculate how many flights are needed with your schedule. The really good thing about Silver is that you get into their clubs without paying a membership fee - something AA doesn't want to know about.

BA also uses a rolling year for determining Silver, where AA uses a calendar year. While I'm EXP a little problem with prostate cancer has kept me from flying in 2004 until now. Won't have a chance to make EXP and am lifetime PLT so I'll make Silver on BA with a RTW and save the Admiral's Club fee. In 2005 I'll look and see where I am and use one or the other based on who provides the best deal.

CX has been very good in recognizing Emerald status with F check in at HKG (it's designed the way all F checkins should be) and the F lounge, which is very nice. Also good for awards - it's been there every time I needed them. Unless there is some benefit for CX I don't know about (other than awards) I would look at AA or BA.

Overall, I would work out your projected flights for 2005, including class, and then work out how fast you will move up with each. They do provide a class bonus to where you can make Emerald, for example, on AA with 66,667 miles if you only fly in business. Definitely a time for a spreadsheet - you might find a pot of Emerald in one of the programs!