Though strictly speaking it wasn't a OW lounge, I used to love BA's Concorde Room in JFK T7, especially when its cigar room was still open. The Chelsea in T8 is ok - good Champagnes - but otherwise could be a 4* hotel bar and restaurant in any major city.

The QF F lounge in SYD will always be a favourite for its design and view of the apron. Same design in the LAX one but no views. I also like the QF J lounge in SIN, though it can get crowded.

The CX Pier (and F section of The Wing before it closed for refurbishment) are terrific. Also like the CX F lounge at LHR T3.

I know everyone goes on about the QR lounges in DOH. I'm not a huge fan, though I do like its premium lounges at LHR T4 and SIN.

Surprised the op doesn't like the BA lounge at FCO. I think it's one of the better ones. The LHR T5 BA F lounge and CCR are ok, with the huge plus of F Wing check in and security.

I also like the AY Platinum Wing at HEL. I've never used the sauna but which other airline lounge in the world serves reindeer burgers?