Khev convinced me... ALIENS is better then ALIEN
I'm not dying on the battlefield that Cameron made a better film, I just prefer it. Like a-dev said we're talking two great films here. Picking a favorite is like choosing between SW and ESB but moreso with ALIEN/ALIENS might just come down to which genre you prefer. One more thing that Cameron did that I love is that he really did make a film that functions just fine as a stand-alone piece. Countless films have begun with characters who have seen or survived some menace and then try to explain to others just "what we're dealing with" as the threat unfolds throughout the film. Carpenter's The Thing, Predator, Texas Chainsaw remake, even Mr. Futterman in Gremlins. People who have some backstory with the monsters that help the new characters get up to speed but that doesn't require viewing a prior film. I thought it was very elegant how in the beginning those who aren't familiar with the events of ALIEN all have to make the most sense they can out of Ripley's report and then everything shifts and the audience collectively (new and old) upgrades to "Ripley status" right along with Hicks and the others and stays on that level for the rest of the film.
I do agree that it takes a little while to get there though, and that it takes some effort to hang in there through the documentary approach when nothing exciting or particularly artistic is occurring on screen. But oh the pay off.