I say Alien are better.
In AvP2 game:Effective Vision.
Strong Attacks.
Stunning
Pred in AvP2 game:Slow.
Too many vision.
Plasma noobs
In movie alien:Killed 2 pred and survived the celtric pred net.
Hyper Speed
Camoflage in darkness
Even a small facehugger killed adults.(like An adult vs a baby)
In movie pred:Vision is very poor.Cant see far.
Slow
Why is Scar so stupid to mark his mask in the middle of a war.He should have done it AFTER he have escaped.
Preds are like....think very unfair.Juz becuz they lose.They throw tanthrums and self destruct.
So we are forced to conclude:Aliens or better than predators.