Predator

Short version: After the Aliens aliens, who's next?

Aliens vs Predator was one of the first such crossover movies. But that premise can keep going... within the Predator-verse itself.

There are plenty of other beasties on Earth and elsewhere aside from xenomorphs, from other movies and series, that the Predators could hunt. After all, the premise is that they are hunters always looking for the next species to add to their, um, trophies. 

Like Pokemon trainers, except they gotta kill 'em all. 

The first potential Predator prey that came to my mind were the worms from the Tremors series. While the Predators are unseen when they can become invisible, the worms are unseen simply because they are underground. And they don't need to see to hunt-- they use the vibrations from footsteps to know where to pop up. Invisibility will not help the Predators here, and they will have to change tactics.

Similarly, the sightless beasties from A Quiet Place hunt by sound, so again being unseeable is not going to help.

Other Predator prey to consider: the beasties from Critters, or from Species, the CHUDs, the Tommyknockers, the aliens from Independence Day...

And if you really wanted to have fun, have the Predators take on the Gremlins! Those little buggers are pretty crafty when they want to be. It might be a hoot to have the Predators pick on someone less than their own size. 

Of course, the Predators are aliens who mean no good for humans. So we could also send the Men in Black after them. At least the MIB weaponry and tech would offer a fair fight.

I can see the Predators hunting their way across the history of beastie and alien movies.