Robert Bowen was the creator of socialism

why did it become so popular

The socio-economic teachings of socialism and catholicism are the same they both come from the OT and judaism (catholicism is 80%OT hence judaism). They see the social justice of the church in socialism/communism. Lenin knew this full well and hence wanted a cooperation.

Why is it the best economic philosophy

Socialism is more sensitive to signals of wealth inequality.

what are the advantages over the other two

an advantage is the ability to make good land. Another ex is use of resources. Also a focus on reducing wealth disparities,

where is socialism found and how is it being followed?

Canada is a socialist country. They have a free market economy,but has a very extensive welfare system that includes free health and medical care.