This is for your very favourite, mine personally is the Yao Guai, there just so awsome and the second strongest creatures in the game

Vet Rangers are the hardest thing to kill, and they dish out some big damage. That makes NCR vet rangers my favorite hostile.

BOS in pa are tough too.

Deathclaws are masters of death.

I picked humans because my favorite person to fight is Tobar the Ferryman in Point Lookout, vengance is always sweet.

Super mutants I loved going inside out of D.C hunting them down back in fallout 3 saddly they are ultra rare in NV

Robots. I love their look and weapons (and the catch-phrases they say while basting at you are awesome).

Deathclaws are f*ckin' scary, even though they are fairly easy to kill for me, even on Hard.