Akuma at his weakest is a man who has trained in martial arts as a young kid. Daniel at his weakest was just a new york citizen.
At Akuma's strongest he is seen travelling super human speed, being able to appear underwater and destroy a submarine with a punch and an island with a punch sent into the ground.
At Danny's strongest (Not sure which series that was in I only own The Director's Cut ) http://www.comicvine...cut/4050-50791/
But I hear he took a nuke (well his chi did) But taking a Nuke is different than taking out an island in my opinion as there is no Nuke that could destroy an island, it would just decimate the surface only.
Overall I say Akuma wins in all scenario's as it would boil down to the Raging Demon and if Iron-Fist can "empty" his soul. Oh and fireballs and beams will help too.