Very much going to depend on your circumstances. I moved from Melbourne to London in 2010 and credit all flights to QF with credit card spend to BA (with a BA Premium Amex). Have taken advantage of the QF Double SC offers last year and this year, so am very close to LTG. Despite the poor earn on partner airlines, this has served me well.
Once I obtain LTG? I'll probably just stick to BAEC for flights and credit card spend.