Predators, all the way, can take getting an arm cut off, get 5 shot gun shots, getting a gun-powder arrow-thingy hit right in front of you without burning your face, getting stabbed through the back and are still yelling at you opponets, can just walk through a fire fight, and can kill a billion aliens, then have the f**king gov't come and ruin his streak
Aliens though are not weak, but have no strength compared to a Pred, and predator can inflict a shit-load more of damage.