Predator 1. Though Pred 2's was easily as good, I just think that the first one I ever saw will always be the one I think of when somebody says 'Predator'.
As for AvP, flappy skin, always had his mandibles parted like a retard who can't shut their mouth, too bulky, dreads looked weird, and he generally looked too human.
AvP-R; liked it more than AvP, but not as much as the originals, because we didn't really get to see him too well, he was wearing the stupid metal sandals, and his mandibles were too big, they just looked silly, sticking forwards from his face like they did.
So I like P1 most, AvP the least, and if AvP-R had been less dark, and Wolf had shorter mandibles, he could possibly have become my favourite.