Well if you want the best, you need to look into the Lost Tribe. At the end of Predator 2, nine predators showed up. Each with a unique look and Neca spent a couple of years making every single one.
8 of them have the super articulation: double knees, ball hips, ball waist. One of them, Elder, has out dated standard articulation.
The must haves?
Stalker (his brother)
Warrior on the left (my favorite of the group only one with blue translucent skin) Guardian on the right
In addition, Toys R Us right now currently has a two pack with a super articulated Classic Predator and a battled damaged predator from the second film.
And Series 7, which should hit any day now will have the masked Predator 2, which is a beauty and must have.
Collecting these are pretty addicting once you start because they did such a great job on each one.
Pretty good guide if you want to see the other Lost Tribe members