I definitely want AvP 3 if they can do it justice next time. With how loved Aliens is, I'm really surprised they didn't just try to emulate Aliens with the AvP movies (or any of the Alien sequels tbh). It's a great foundation to reboot AvP and Colonial Marines fighting Aliens and Predators would make for a far more entertaining action movie, than scientists in the Antarctic or teens running around a small US town.
Weyland-Yutani scientists on a colony get hold of some Alien eggs and start experimenting / breeding them, something goes wrong and the company have to send in the Marines to investigate and hopefully salvage their research. A Predator ship is alerted to the Xeno outbreak and see a great hunting opportunity. Similar plot to Aliens but with 3-4 Predator's hunting Aliens and some wisecracking marines caught in the middle.
If they wanted to do the team up thing, they could do it with a couple of badass marines, teaming with the last 2 Predator, as a last resort to survive. Simple plot no need to make it complicated. Just make the action good, with a bit of gore and some good one liners. There you go, a decent AvP movie.