I tend to study Indigenous Australian experiences, so I'm not widely read on migration history.

That being said, the book Tyranny of Distance, an Aussie history classic by Geoffrey Blainey, answers this and more by exploring the ways in which Australia has been shaped by issues concerning distance.

According to Blainey, Australia and New Zealand were far less attractive destinations than the US or Canada, and the primary reason is that the journey to North America from Europe took several months as opposed to several weeks. The First Fleet of British colonists took eight long and arduous months to reach Australia in 1788, across three oceans and past several reefs, and it was an incredibly uncomfortable journey in which the likelihood of dying from illness or disaster was significantly higher than a trans-Atlantic voyage. A half century later, new ship designs and routes saved health and time, and British regulations concerning long-distance passenger transport made the ride more comfortable, meaning if you didn't mind months of on-board living, a migrant's trip to Australia actually became far more pleasant than one to North America by the middle of the 19th century.

A bigger issue was cost. It's obviously far more expensive to travel to the opposite side of the Earth than to 'cross the pond', and this meant far fewer people could afford to migrate to Australia - especially the poorest folks who would be the most eager to seek a new life in a prosperous new world. So few working class people migrated to Australian colonies that their economies lacked free labourers, and since a family was much more expensive than a single person's fare, young bachelor men dominated the population of Australia until around the First World War, especially out in the colonial frontier where there were essentially zero white women. Most labourers prior to mass migration were ex-convicts or Australian-born, and wielded enormous power compared to most working class populations at the time, being able to work wherever they got the best pay and conditions. They were expensive, unreliable and oh-so-uppity to their social betters, and this became an important aspect of Australian identity - Australia remained a bastion of worker's rights, trade unionism and blokey toxic masculinity up until around the 1990s.

The wealthier Britons who migrated in the hopes of becoming new world gentry were encouraged to pay for their worker's fares too - this was the scheme used for the first free settler colony, the Swan River Colony in Western Australia (1829), which gave land equal to the value of the labourers or machinery you brought with you from England. This was a disaster - most of Perth is dirty grey sand, so land grants were mostly long thin infertile strips fronting the river, with maybe less than a fifth of it having a patch of fertile alluvial soil. With employers and the colony failing, it was in the best interest of the labourers to jump ship to the thriving colonies of Sydney and Hobart, becoming a wasted investment for the landowners.

Eventually, the destitute gentry bit the bullet and requested convict labourers to be shipped to Western Australia, but convicts aren't free - they cost a fortune for the British government to transport, feed, clothe and guard. A much better solution soon came from a dodgy Englishman called Edward Gibbon Wakefield, who proposed that land should be sold at artificially high prices, rather than given freely, and colonial governments should use this revenue to subsidise the fares for working class people. This had the bonus social effects of ensuring that only true gentlemen would own land, that the workless masses of Britain could fill the labour shortage in Australia, and that dirty thieving convicts would rot in prisons instead of working in luxury. This policy proved a success with most Australian colonies, netting the (until then) destitute colonial governments enormous revenues - yet migration drastically increased with the gold rushes and economic booms from the 1850s to 1890, meaning this revenue inevitably funded less and less migration as the 19th century came to a close. Assisted migration would be resuscitated again after both world wars, bringing veterans to farm remote Australia, but with many Australians out of work, and most migrant farms failing, it was never a popular scheme. It would also be remiss of me not to mention that until the 1970s Australia's migration policy was highly and vocally racist, only accepting white British migrants.

Australian and New Zealander land now cost a fortune to purchase compared to North American land, which didn't need to fund labourer fares, but the great working environment and spirit of egalitarianism meant you might be able to earn enough to buy some land eventually. A worse issue is that once you migrated, if you were working class you were pretty much trapped here - the fare back to England was just as expensive and completely unsubsidised. Other benefits included less overland travel and generally better living conditions than in the US, with Australian cities being fairly pleasant and modern once they got going, and never having to deal with the overcrowded slum conditions of American port cities like New York. Another incentive that is less specific to Oceania might be family - if you are spending a fortune to buy a new life, it is safer to do it working with family who are already established there.

IMPORTANT EDIT: the timing of gold rushes would also be important. Many of Australia's cities received enormous waves of gold-seeking migrants that would otherwise have been heading to North America, similar to the boom that created San Francisco in the California gold rushes.

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So, TLDR:Incentives = comfier trip, your fare subsidised, great wages and working conditions, fairly egalitarian, not forced to live in dirty old New York, family.Disincentives = much longer trip, more dangerous, more expensive, land too expensive, stuck here, funny accent (New Zealand), maybe the shame of the convict legacy.