Saying that the USMC are the best infantarymen in the world by a mile is somewhat misleading...the royal marines aren't famous for nothing...and there are also quite a lot of marines in the US as opposed to UK
I hate to admit it but thats true. For their size they are the best infantry in the world however. Ive known many British Marines and they are trained above our level. However just like SEALs they are a far smaller force.