This is anthor thread is the vain of Best Unit of WW2 and the civil war so now we have Vietnam
My personal thought is the Austrlaian SASR group which achevied a huge amount with their kill ratio of 500-1. They become known as 'Phantoms of the Jungle' by Vietnamese Communist forces, attributed to their cunning and fieldcraft. Throughout the war they provided usefull intelligence as well as as doing ambushes which was what needed to be done in that enviroment rather then the us tatic of search and destroy.