I actually liked AvP: Requiem due to the fact it was actually ALIENS fighting a PREDATOR. Granted, I could have done without the rednecks and the teeny-bopper bullshit, but the Predator was pretty badass in it. I loved how you can see him getting gradually more and more pissed off as the situation grows more and more out of control.
Alien vs. Predator I didn't care so much for. I thought the idea of Predators being worshipped by ancient humans interesting, but the pyramid below the ice and PG-13 action were just too dull.