Taken as a stand alone Aliens Game, Alien Trilogy was solid enough...
The trouble was Acclaim really hyped the backside off the Motion-Capture aspect, which had no real impact on the in-game sprites, sadly, plus UK magazines like Mean Machines over hyped just what an impact game would have on likes of Jaguar AVP.
For myself Argonaut with Alien Res. provided the true console Aliens game of the PS1 era, something that not only pushed the hardware to the max, but really understood what Aliens fans wanted from a game...i'm still thankful they had the vision to cancel the 3rd person game and start from scratch for the FPS game.
Sadly game was nigh on unplayable without a PS1 Mouse, so you needed deep pockets to get the best from it.
Rebellions original AVP set THE benchmark for Alien/Predator games, Monolith had a fair crack at a sequel, looked fantastic, but the A.I routines for the Xeno's just totally failed to understand what was needed to make them fearsome.
Less said about Alien/Predator games since then (Isolation, Concrete Jungle, Rebellions AVP games on console/PC/PSP, etc..the better)