Always a bit of a grey one, as it doesn't seem to be written down anywhere officially where who gets pink tags or orange. My experience generally:
- Qantas Club get orange priority.
- SG, WP, CL get pink business.
- WP, CL get yellow F tags when on a flight with F.

Some ports are better than others at doing this. At the end of the day, they don't do anything to make your bags come out quicker though (especially in MEL and PER i find).