QF (or non stop EK) will work nicely. A relatively short sector to DXB to wine and dine, then a long sleep to SYD should see you comfortably into a SYD morning. The Asian stopover is good in theory, but the short second sector to SYD will leave you short on sleep - this makes the BA & SQ (and to a lesser extent TG and CX) a crappy option.
That only holds true on the way down to SYD. From SYD to LHR, you get much more sleep via SIN than you do via DXB.