Based on my most recent experiences (May, June and July of this year), I would take QF over CX and BA and CX over BA.

QF now has an excellent F product, much better than it was when I first flew QF F in 2002. CX has been slipping over the past two years. It was excellent in 2002, 2003, 2004 and 2005, but last year and this year, I've noticed cutbacks in the menus and an intangible sense that it is just not what it used to be. It is still quite good, but not like it was.