Yes, "Aliens" is the sequel to "Alien." Directed by James Cameron, the film was released in 1986, seven years after the original "Alien," directed by Ridley Scott. While the first film is more of a horror thriller focusing on survival in space, "Aliens" shifts to an action-oriented approach, featuring Ellen Ripley, played by Sigourney Weaver, as she returns to confront the alien threat with a group of marines. The sequel received critical acclaim and is considered one of the best sci-fi action films of all time.

In "Aliens," the planet referred to as "Romulus" does not directly tie into the plot. However, the term may be confused with "LV-426," the planet where the events of "Aliens" take place. The film explores themes of survival and motherhood as Ripley confronts the alien species. If you meant a different context regarding Romulus in relation to "Aliens," please clarify, as Romulus is not a character or location in the movie.

Opinions on the best film in the "Alien" franchise often vary, but many fans and critics consider "Aliens" (1986), directed by James Cameron, to be the standout. It successfully blends science fiction with action, featuring strong character development, particularly of Ellen Ripley, played by Sigourney Weaver. The film's suspenseful pacing, memorable quotes, and groundbreaking special effects have solidified its place in cinematic history. While other films in the franchise, such as Ridley Scott's original "Alien" (1979), are also highly regarded, "Aliens" is frequently celebrated for its impact on the genre.

"Alien: Romulus" is not a direct sequel to "Alien: Covenant." Instead, it is an upcoming film in the "Alien" franchise, set to explore new characters and storylines within the established universe. While "Covenant" is part of the prequel series leading to the original "Alien" film, "Romulus" aims to expand the lore and may introduce different themes and narratives. The film is directed by Fede Álvarez and is expected to offer a fresh take on the franchise while still being connected to its roots.