I recall watching Alien on the big screen in Los Angeles in 1979; it scared the hell out of me (I was not a teenager yet).
None of the follow-up movies scared me in the slightest, though, Aliens was an intense movie - for its time.
That said, I have to agree with the statement made about the "unpopularity" of certain Alien renditions; I prefer the Alien from the original movie - Giger's Alien; the rest weren't... scary. They simply looked like someone went wild with a box of Lincoln Logs, Lego's and a hot-glue gun.
So my question is thus (reiterating what another said): Would you be willing to re-render the Alien to make it look closer to Giger's, or are you stuck on playing with Lincoln logs, lego's and a hot-glue gun?