If BA's GF at T5 is among the best OW lounges, there must be lots of really bad lounges throughout the alliance. It's overcrowded and the food is medicore at best. It has good views though.
I am a fan of CX's HKG lounges. Not a fan of the Al Mourjan in DOH because of lack of comfortable seating and crap showers.
The QF lounge in SIN is one of the better OW lounges I have visited. Decent food and relatively roomy.