If I may throw in my 2 cents about the fights in both films, I would say the Celtic fight is quite good, the part where the Alien is swung around amps me up. Though, it does feel somewhat like they just stepped into a ring and someone rang the bell and said "Round One", I must agree.
I think the main reason Predators swat Aliens like insects, especially in AVPR, is that they are experienced and seasoned at it, Wolf more so I would imagine.
Thats what I take from it, their experience in hunting Aliens, the way the Aliens move, leap and their general capabilities would be passed through experience and their generations. No biggie for me there.
Suffice to say most of the fighting in AVPR is done at a distance with Wolf's Plasma Cannon, the scenes like the sewer fight where the Predator rises holding two Aliens were good. They look cool, what can I say, I am a Predator fan after all. Plus, I hardly think that particular scene could have been done in the reverse.
Aliens are fodder when it comes to 'versus' stories, lets face it.
In numbers, they are viral ('Aliens', 'Alien: Res', 'AVPR') - attack indiscriminantly, are brash and abduct healthy hosts for implantation - and alone they are far more geared for survival ('Alien', 'Alien3') - stealthy and defensive.
