I like BA as my second FF program. Am EXP on AA, but loose that this year because of medical problem. Just started flying on the back half of a DONE4 RTW ticket and made Sapphire while flying from the US to Australia. With careful planning I can make Emerald on BA one one DONE4. Love the Sapphire with BA as it includes lounge membership. The other reason why I went with BA over QF is that I started working on Sapphire the day I started flying. QF starts counting on the month you joined and AA is on a calendar year.

BA also works well for me in that I can cross the pond in a very comfortable business seat!