First there is no BEST, because they differ in roles. Whereas they are all Special Operators their roles are not the same, by so it's almost impossible to say “who is the best” but let's see HOW they differ. read more
Delta Force is an Army outfit that primarily selects candidates from within their own special forces and infantry units. However, they will also select candidates from all branches of service, including the National Guard and Coast Guard. SEAL Team 6 selects candidates exclusively from the Navy's SEAL team community. read more
Navy SEALs, like Delta Force, are super soldiers specially trained for unconventional warfare, reconnaissance, and counter-terrorism operations on SEa, Air and Land (hence their acronym moniker). Created by President Kennedy in 1962, the Navy SEALs emerged from the elite of the U.S. Navy to parallel the Army's Green Berets, when tasked to infiltrate and disable enemy jungle camps during the Vietnam War. read more