Having now visited all the Oneworld HKG lounges my favourites in order are:
1. Cathay The wing/pier
2. Qantas/BA (best in mornings - as I have just thanks to BA had an opportunity to sample the morning offerings)
3. G16 Lounge
4. JAL Sakura Lounge
Quite a trek through the airport if you want to do them all, The Pier & JAL Lounge is accessible by transit but you have to walk back, all the others are in the main area but a bit of a walk apart.
If you want my opinions on BKK lounges let me know as I have done most of them now as well.