There is no definitive answer to this question as homeschooling is popular all over the world. However, there are certain countries where homeschooling is more prevalent. In the United States, for example, homeschooling is estimated to account for between 2 and 3 percent of the total student population. In Australia, the figure is thought to be around 1 percent.
In many European countries, homeschooling is far less common. This is partly due to the fact that most countries have compulsory education laws which require children to attend school. However, there are some European countries where homeschooling is legal and more common, such as the Netherlands, Germany and Sweden.
So, while there is no definitive answer to the question of where homeschooling is most popular, it seems to be most prevalent in the United States and Australia, and more common in certain European countries.