I do agree with most of the advice in this thread; the affordability of living in a specific city depends on your personal spending habits and lifestyle. Cities also have different salary ranges, depending on the occupation and job opportunities. Ang napansin ko na big difference in cost of living between Sydney, Melbourne, and Brisbane are the rent. Yung cost of food and transpo, depende sa location mo in the city.
Since I'm an international student, I prefer to live closer to the city or university para hindi haggard tuwing papasok sa school. Naranasan ko magcommute ng more than one hour from southwest Sydney to city almost everyday for 5 weeks, only to realize it was not sustainable for me kasi nakakainip at nakakapagod (lalo na kung may mga bitbit na books at laptop). Most people would be willing to commute kasi mas mura tumira sa malayo, pero iba din kasi ang preference and priority ko. So kung lilipat kayo sa sa Sydney or Melbourne wherein mahal ang accommodation sa city, i-consider nyo nalang which type of person you are. Like willing ka bang magcommute para makatipid sa rent, or increase the budget for rent to shorten travel time? For my own room right across uni, I paid AUD 230pw, whereas in Brisbane I'm paying AUD 205pw (it's 2-3 suburbs away from uni). I paid roughly AUD 30 per month for transpo since I just walk to uni and I travel infrequently (bumabiyahe lang ako pag maggrocery or gagala).
I'd say costs related to transpo depends on your routes. Kung nakatira ka sa malayo, mas mataas ang transpo cost, but if you live a few suburbs away lang from your uni/work, it should be relatively cheap (maybe AUD 3 to 4 per trip). Food and grocery expenses can be kept really low if you cook most of the time. Eating out is expensive, so you need to include that in your budget if you like trying out new places to eat (AUD 20 to 30 per meal). May slight difference ng price when eating out, but this depends on the restaurant. In Newtown (Sydney), you can find good but affordable food (like AUD 15 for pad thai, for example), but in Brisbane it's around AUD 18 to 20 for pad thai. Having stayed in Melbourne for at least 3 weeks, I feel like food in Melb was slightly cheaper than Sydney. Cost of shopping for items, palagay ko wala naman difference across the states (like if you shop at Coles, Woolies, KMart, Target, Big W).
In terms of lifestyle and culture, I actually like Melbourne because of their arts-centered vibe. I planned to move there after studying in Sydney, but pandemic happened and I ended up in Brisbane. I haven't explored Brisbane much because of lockdowns, but I feel there's not much to see in the city (unlike Sydney's tourist hotspot: Opera House, Circular Quay).
One big thing I noticed in Brisbane is that there are fewer asians here than Sydney or Melbourne. A friend who moved to Brisbane from Townsville said that puro caucasians daw sa Townsville, so she experience a bit of discrimination doon just because she looked different and did not grow up in that community. Townsville is apparently a small town so maraming magkakakilala. And that was in the context of a workplace. Not that I think it should be a deciding factor on where to move, but I figured it would be good for people to know that not all Australian cities are the same.
If you prefer a more culturally diverse environment, definitely go to Sydney or Melbourne. Of course, the large presence of ethic communities in these cities translate to more options for dining and shopping (restaurants and asian groceries). In Sydney, there are tons of asian and Filo groceries (Ingleburn, Blacktown, Hurstville, Kogarah, Haymarket, etc.) which have a wide variety of products. Here in Brisbane, there are fewer places to shop and some products that I've bought in Sydney aren't available here.
Yung nabanggit na discrimination based on where you live, I don't know if they really discriminate here based on where you live. Some people could be living in more affluent suburbs because they can afford to buy the house or they've simply inherited a house that's been in the family for generations. Eastern suburbs (Bondi, Double Bay, Vaucluse, Coogee) and Northern Beaches have higher rents kasi views ang binabayaran mo, including access to the world-class beaches. Houses are relatively bigger and newer too. Where you live depends on which kind of lifestyle you're after. Kung mahilig ka mag-surf at magswimming, living in the Eastern suburbs might make more sense for you (kahit mas mahal ang rent), pero kung homebody kayo at hindi naman kailangan nakatira malapit sa beach, living in Inner West or even Western Sydney is okay (cheaper rent).
