Horrible match-up for Aliens here. As much as I love Aliens, I have to go with The Godfather Part II.
It's strange, because both films have produced the heated "it's better than the original!" argument, but The Godfather II is superior to Aliens in every way. Directing, acting, and writing. You name it, and The Godfather II still surpasses Aliens. Al Pacino delivers a masterful performance, as the evil and cold-hearted Don. And you can make an argument for Robert De Niro as the better Vito Corleone.
Upon its release, The Godfather was considered to be the standard for American filmmaking. It's surpassed expectations, and eventually, The Godfather became one of the most influential films in the history of cinema. And despite all of the overwhelming amounts of tremendous praise, The Godfather II STILL challenges the original, as the best film in the series. It's an impressive feat, that deserves admiration.