Hi Zarah, welcome. I'm personally with HBF and haven't been able to fault them since I got coverage. I'm a big fan of members-funds, they seem to cover more as standard. They covered the hospital fees for my sleeve and I was out of pocket $4000 to be sleeved privately with Dr Yong in Joondalup, WA. My current hospital cover is about $50 a fortnight, but it's definitely not the cheapest option. Mine includes extras cover and it's for a private room. Though I did take out PHI before I turned 30, so there may be the extra loading for you since you're over 30.
Unfortunately from what I understand, all PHI will make you wait the 12-month waiting period as the sleeve would be for a 'pre-existing' condition. There aren't many operations they'd waive it for.