You may not include every movie for your optimum watching experience but which order do you prefer?
Release order: Alien (1979), Aliens (1986), Predator (1987), Predator 2 (1990), Alien 3 (1992), Alien: Resurrection (1997), Alien vs. Predator (2004), Aliens vs. Predator: Requiem (2007), Predators (2010), Prometheus (2012), Alien Covenant (2017), The Predator (2018).
Chronological order: Predator (1987), Predator 2 (1997), Alien vs. Predator (2004), Aliens vs. Predator: Requiem (2004), Predators (2010?), The Predator (2018?), Prometheus (2093), Alien Covenant (2104), Alien (2121), Aliens (2179), Alien 3 (2179), Alien Resurrection (2381).
Not sure on the in-universe dates for Predators and The Predator but I assume The Predator comes afterwards.