Hi, I've just enrolled in several frequent flyer programs: QF, SQ, UA, SA
and CO, and I've already got nearly 90,000 miles with CX's asiamiles. I
will be flying on Emirates, Virgin Atlantic, Qantas (N class) and Air New
Zeland on HKG-LHR from this month, which means it's impossible for me
to earn asiamiles anymore. So from the above FFPs, which one would
you suggest me to stick to in order to earn as much miles as possible?
Here are the details of my flights from this month:

Apr19-Jul1: Emirates HKG-DXB-LHR (Booking Class: K)
Sept1-Oct13: Virgin Atlantic HKG-LHR (Booking Class: X)
Oct28-Dec18: Qantas (Booking Class: N)
Jan8-9Feb: Air New Zeland (Booking Class: Currently O/E, may change
to the lowest economy when fares are opened)
18Feb-30Mar: Air New Zeland/Virgin Atlantic (Booking Class: X)

Thanks for reading and helping!