Having visited the two lounges a couple of months ago, We felt neither one was significantly better than the other, the QF lounge seemed bigger with more food options but we were only in there for an hour or so as it opens before the BA lounge. (We were VDB by CX so had a few hours to kill at SIN). However by the time we were leaving the BA lounge for BA16 the lounge was full with people standing due to a lack of seating.