Biased review without any spoilers. In my teenage years, and due to a local hangout drive-in, I viewed the first Alien movie more than any other in my 60-year life. I have watched *multiple times* all other Alien “franchise” movies including the Predator variations.
As a long time Alien fan, I enjoy all the Alien films. I loved the more recent prequels, Prometheus and Covenant, because it told an origin (and original) story that was new. In the release of Romulus, my YouTube feed filled up with “what was cut from Prometheus” and “what the Engineer said” (or could have said based on cut scripts and scenes). I suggest you seek these out only because it fills in a number of holes left up to audience speculation.
People want to force rank these movies, which I guess serves a purpose. While it might be “recency bias”, as I walked out of Romulus I thought “top three”. Why? Romulus is a fan-based movie. There were lots of sweet spots and recognizable call-backs to dialog and action that some feel more derivative than they should be… but for me? Mixed with the newer elements towards the alien canon? Highly enjoyable, watchable and rewatchable. For viewing Romulus, it is best to have seen Alien, Aliens, and Resurrection for the dialog and action easter eggs. Top four ranked: Alien, Aliens, Romulus. Prometheus (previously third). Biased? Yes.