I guess, in hindsight, I have a weak spot for stories where the horror is not that everything is out of control, but rather, that everything is under control.
Got mine from a used bookstore for fifty bucks. It's written entirely in-universe, introduces all sorts of neat lore about the political situation, and best of all has little blurbs from "real" Marines that sometimes contradict the official text. Oh, and it's got a glorious cutaway of a Cheyenne.
The author, Lee Brimmicombe-Wood, normally worked on wargame documentation so all the weapons, equipment, vehicles, & even starships he describes feel remarkably real. The last chapter is a series of transcripts of Weyland-Yutani personnel studying the xenomorph and figuring out how to weaponize it