Sweden
That would be your own if you adopt a foster child.
India was the first country in the world to adopt family planning as a nation-wide programme in 1952.
France
The USSR and Red China.
Africa
Malawi
USA
Virginia
It depends of course what is best for you the fastest way to adopt or the cheapest or the simpliest way to adopt. But still it is being south asian countries like Vietnam or India to adopt babies.
No other country will ever, nor should ever, adopt the US Constitution.
If you live in Australia, the only avenue for adoption open to you is inter-country adoption (unless you wish to formally adopt the child of a deceased relative). The Philippines is the "easiest" place from which to adopt, but inter-country adoption is an arduous road, no matter which country you attempt.
How do you adopt your spouse's children if they do not have legal status in the United States? How do you adopt your spouse's children if they do not have legal status in the United States?