I guess Samsung phones are more popular outside US.
Among my colleagues, of 10 smartphones, 8 are Samsung ones (includes 3 Samsung Notes) and only one iPhone4S.
Our split is fairly even (I lead a mobile dev team in London, both Android & iOS). Maybe it's a demographic thing: most developers have a Galaxy Nexus, and they don't really see any compelling reason to move on to the S3 right now.