Ummmm, either soccer or basketball. Maybe I guess it's soccer. Since you don't need much equipment. Because in poor countrys such as Africa they just like put thre shoes to make a net and they can use a pop can to use as a ball. Or you can just take off your shirts for nets. And a round object for the ball. And for basketball, you need more money since it needs more equipment such as the basketball net, basket ball, jerseys ( Not to confuse players on what team they are on ). I guess thats about it.
Soccer. There's a soccer world cup, but no rugby world cup. =] Also, the British brought soccer along with them when they colonized countries, leading to these countries being introduced to the sport.
it is actually soccer, as all of china is soccer fanatics, India has some... but not many, all the south american countries are soccer people, I know the British isles are also soccer people. So that is a lot of soccer loving folks.