Aliens, because it is pant-wettingly scary and far superior to Alien, even though that was magnificent. And I HEART HICKS. Yay :3
I also prefer the second of the Jurassic Park films. I very much bought into the second island concept and the scene with the T-rex and the doghouse hanging out of its mouth when it's loose in San Diego is hilarious. KRONSHE. Tee hee.