Don't know if they are definitively 'the best' but I have only used
www.1cover.com.au/ exclusively for more than a decade now.
Only had one claim, I had some medical bills and an early flight out of Fiji once when I got busted up on coral and the wounds turned septic. The paid up quickly and without many questions.
I used them just last night, it cost $253 to comprehensively insure two adults and a child for 5 weeks in Indo. That policy has a $100 excess on claims.
You biggest problem travelling to Indo right now is that the insurers all seem to have an Ash Cloud Exclusion on the policies issued after 3rd July 2015.