1.Alien /Aliens (phenomenal)
2.Alien 3 (very good in its own way)
3.Alien Covenant (good)
4.Alien Resurrection/Prometheus (good)
5.Predator/Predator 2 (very good /good)
6.AVP (its fun to watch, not to be taken too seriously)
7.Prey (ok,enjoiable)
8.AVP2-R (kind of shit, but if you turn off your brain you can enjoy it/not to be taken too seriously)
9.Predators (not implemented very well, could have been much better)
10.The Predator (very bad...no brain to switch off)
(this is just my personal list and shows how important these films are to me)