When I was a young fellow I decided I didn't want to live in Canada anymore. Too hard to find a job there, especially Vancouver which attracts a lot of people looking for work because of the mild winter climate there. I wanted to live in a sunny climate that doesn't have a long winter. Southern California was ideal because it had a Mediterranean climate, good beaches and great gyms. Not so good with all the air pollution. Canadians can visit the USA but getting to live there wasn't so easy. Honolulu would be at the top of my list but getting to live there is difficult because they have special conditions even for other Yanks.
I concluded that I wanted to live in a country that spoke English, wasn't extreme re religions, had a nice climate and good beaches. I also wanted to live in a big city so I could do my own thing. I found small towns too limiting socially and professionally.
My short list of cities that satisfied my criterion were Los Angeles, San Diego, Honolulu, Miami, Atlanta, Sydney, Perth, Brisbane and perhaps Adelaide. Melbourne was close but the beaches there leave a lot to be desired compared to Sydney.
When you consider the beaches you have to take in the water temperature. In Sydney the water is cold for most of the year. Ditto for Melbourne and Adelaide. Brisbane is on a river but there are great surf towns not very far away. You have the Sunshine Coast to the north and the Gold Coast to the south. The water in the summer is about 24 degrees. In Sydney in the summer it is 21 plus or minus a degree or two. Forget about Melbourne and Adelaide. The Southern Oceans are cold. Perth is fine because a warm current comes down from the north.
I suppose Darwin, Cairns and Townsville are alternatives that qualify for most of the points I mentioned. Virtual summer all year in those places.
In terms of physical surroundings Sydney is blessed compared to any other city I have seen. Vancouver, BC, is great but it is too wet and miserable for about 7 months of the year. Nice in August and September.
Sydney has flowers blooming all year around. The winters are colder than up north. Brisbane is on a similar latitude to Miami so that should tell you a little about the climate up there. Sydney, Perth and Adelaide are on a similar latitude to Los Angeles and Atlanta. The climate in Sydney is similar to northern Florida or Southern Georgia in the US.
As far as socially well, take your pick. Plenty to do and see in Sydney. There are at least 20 major beaches in Sydney and heaps more south and north of the city. There are over 5 million people living in Sydney or nearby. Melbourne reminds me of Toronto. Both on Harbours but not directly on surf beaches. Both have trams and communities of people from southern Europe. I visited Melbourne a couple of years ago and it had changed so much in 30 years that I was lost. Lots of great buildings there and outdoor life and sport are important. They play Aussie Rules football there but we play Rugby League in Sydney and Brisbane. Quite amazing that Sydney and Melbourne and Brisbane are almost different countries. That is partly because historically each was a separate colony and did their own thing. When the continent became a single country some unification occurred but the differences have persisted and each state has its own character. The first time I visited Queensland someone asked where I was from. I told them Canada but they wanted to know where I lived in Australia. I thought who in the heck cares?!
Foreigners are told about sharks so you think you see them at the beach when you see shadows. There are deadly spiders here but I haven't seen any. You can get big spiders in your house or in your car and they just about give you a heart attack. Flies and mosquitoes are another thing and are pests for about 9 months of the year in Southern Australia.
You have to cover yourself in the sun because sooner or later you will need growths burned off your skin.
The Aussie girls make up for the less than friendly blokes here. There is a deep seated dislike for all foreigners. Yanks will think the Aussies are friendly and like them but it isn't true. They dislike everyone. The males here stick with their mates and it isn't easy to befriend the guys here. Soldiers during the Vietnam War used to come here for rest and rehabilitation and spent money on the Aussie gals and haven't been forgiven for that excess.
The Aussies aren't prejudiced against blacks unless you are an Aboriginee or Indian or a refugee. Then you will cop it. Southern Europeans are called 'Wogs' here. The Lebanese are generally disliked or feared. They also don't like Muslims. You can be born in Australia of parents born here but if you look Asian you are still called Asian!
As far as things to do well you can go camping all year. Swim most of the year and sightsee 12 months. Lots to see and do. You can live in Sydney for 50 years and not see all the wonders that are here and closeby.
The gyms are pretty good and the mild climate makes training worthwhile most of the year. You don't need a raincoat in Sydney and usually a tracksuit will suffice most of the year to keep you warm.
I chose to live in Australia. If you move here from America, Canada or Europe then remember you are a day away via jet. 13 hours to LA and the fares aren't cheap in the busy seasons. You won't find you will visit your homeland very often if you live down under. I am an Australian citizen but not an Aussie. Those who live here will know what I mean. When they find out you are Canadian it makes a difference. The gals like our accent and the Yanks, too.