Daishidan,
Undefined,
19 years ago
Both species are highly dangerous, how deadly they are any given encounter depends on the variables.
My opinion would be on how well trained, battle hardened, and wary the Predator is. I remember a story about an unblooded Predator jumping into the centre oroup of about 20 aliens. Using spear and wristblades he managed to kill most of them, but his arrogance in his abilitis led to his death as he was overcome by reinforcements and as the bugs do, rushed him.
The certain death tactic for aliens is ranged combat. The can't use weapons so unless they're in clawing or whipping distance they can't touch you. But a predator lives on the exhilaration of close combat, of stalking and showing off its martial prowess, of entering into another creature's realm and tearing it apart on its own terms. This is where the Alien's 'natural' lethality more often overcomes training and technology.
Yautja are tough - Aliens are tough, and so are some humans. You've gotta be some kind of messed up to concsiously enter a hive.
Move well or die.