Desdichado
Hero
As much as I like the Lord of the Rings movies, they do have their flaws. I think their strength is the source material on which they're based and their spectacular visual effects. Aliens on the other hand, is a real stand-alone classic. I have to give it the edge in this match-up.
Gah! How in the HELL did either of these two get into the final four? What a travesty! Both of them are teh suxxorz relative to all kinds of better "geek genre" films that are noticably missing at this level of voting. I give the edge to Planet of the Apes just because although it's dated, at least it was clever once.