I could not disagree with you more about Alien vs Aliens. Like the Matrix, the original Alien movie was a fresh take on interesting concepts- in this case, an incredible biology that was great and now much copied for sci fi fans. The sequal was just a dumb big-budget dime-a-dozen fight fest.
I don't know. I think Bill Paxton's performance in Aliens rose it up a level. He was the best actor in either of them and certainly created the most memorable character in either of them. "Game over, man"