My List of OW lounges ranking are a bit biased to QF, but heres me definitive ranking
My ranking criteria is pretty simple and mostly limited to the in-lounge F&B

1. QF FCL SYD
2. QF FCL MEL
3. QF JCL CBR
4. MH FCL KUL
5. BA JCL SIN
6. QF JCL SIN
7. QF JCL SYD intl
8. QF JCL SYD dom
9. MH JCL KUL regional
10. QF QP PER dom
11. QF FCL AKL
12. QF JCL MEL dom
13. QF JCL BNE dom
14. MH JCL KUL dom
15. UL JCL CMB Serendib
16. MH JCL KCH
17. BA JCL BKK
18. CX JCL BKK
19. CX JCL SIN Skyview
20. MH JCL SIN