I've dabbled in Australia and the US. Multiple Sub-I's in both countries (speciality and primary care). Close mentors in both countries. Strong likelihood that I'll match okay in either country for my prefered specialities. That being said, for primary care...
Australia. It's unreal. ABFM Certification transfers. Here's my growing collection of Australia posts:
http://forums.studentdoctor.net/threads/reciprocal-licensing-agreement-with-australia.1203527/
PCPs make about the same as the do in the US, much more if you're willing to practice rural or do some advanced procedural training. (And "rural" in Australia can literally be only 50 miles away from Sydney or Melbourne... or all the way up to Fly-In/Fly-Out outback clinics, which are a whole other level of awesome). Here's a calculator to play with:
https://gpra.org.au/gp-earnings-calculator/
But this calculator is strictly for outpatient work.
One of my rural GP mentors rounded at hospital in the morning, did outpatient for 4 hours, went home for an hour or two to diddle around with his farm, and then came back for some surgeries/procedural stuff in the afternoon (cholyes, colonoscopies, tonsillectomies, etc.). He did admin on Fridays and saw private patients on Saturday. He also did a handful of shifts in the ED every month (in a country where people can see GPs for free--so no bogus nothing). Made a few nursing home visits too. Pulled in north of $700,000/year and skied all around the world Dec-Jan.
And don't forget: free healthcare for life, 8% of salary/year
extra gets socked away in a pension fund, kids go to university for free, no insurance dramas, you can always do what's best for the patient (as long as it's reasonable and evidence-based), minimal paperwork, and Australians tend be very, very pragmatic people--even as patients, which I absolutely adore. "Why's my BP high"? "Cuz you're getting fat mate. Knock off the chips." "Yeah. Fair enough."
It's not all sunshine and puppies, but most of the discontent is over the length and availability of training (which can be 8-12 years for some specialities). But if you've already trained in the US and want to move... seems like a no-brainer (at least for FM).