I have a multi-canon approach:
Top tier / preferred canon:
Alien: Director's Cut, Alien Isolation (with Alien: Blackout as an extension of that story), Aliens: Special Edition, Alien 3: Assembly Cut
Acceptable Canon:
Prometheus, Alien Covenant, Alien: Director's Cut, Alien Isolation (with Alien: Blackout as an extension of that story), Aliens: Newt's Tale (1st act) Aliens: Special Edition, Aliens: Colonial Marines (*events only, not exactly as we see in game, similar to 'Alien Trilogy'), Alien 3: Assembly Cut, Aliens Fireteam Elite
(Absolutely no Alien Resurrection, or AvP).
As for Predator movie canon:
Prey, Predator, Predator 2
(no Predators or the Predator, and no AvP movies)