I would guess because 90% of “The Religion of Pieces” is of the sunni flavor. Just a guess though. Also, soetoro was raised a sunni and never renounced it.
It should also be remembered that the nation with more Shiite Muslims than any other nation in the world (Iran) took over our embassy and held our representatives hostage in the late seventies. If we seem to prefer Sunnis, I don’t think it has anything to do with differences in Sunni and Shiite philosophy. We like oil and we don’t like having our people taken hostage by screwball ayatollahs.