BA J bed is a touch too short for my 188cm - I'm deliberately trying to make my feet fit around the seat infront of me. It's nice being flat, but it's also a bit too hard to lie on.

QF skybed is better for length and the footrest is usable for me.

I'd prefer to use QF 2 LHR-BKK-SYD rather than route through SIN. If trying to overnight SIN-SYD, the 6 hrs flight time precludes any effective sleep (really - only 2 or 3 hrs when meals are accounted for). BKK gives another 2 hrs to sleep.