I like the Predators better. Despite what Ash said in the first movie, Aliens are not even close to being a perfect organism compared to some of the creatures in some other science fiction. Aliens are hostile to humans and Predators but don't have the intelligence to defend themselves properly when the advanced races strike back. This is a very bad combination of traits that makes them lose out when it comes to natural selection and may ultimately lead to their extinction. They've only survived this long because of the stupidity of certain humans and the cultural traditions of certain Predator clans. They can't even colonize other planets without the help of humans or Predators. Because humans have had few encounters with Aliens the humans haven't learned how to properly prepare themselves. The old alien comics and the new novel DNA War show what would happen if Alien encounters became more common. Humans develop special combat teams, robots, cyborgs, androids, toxins and more to deal with the Aliens and the Aliens become nothing more than a minor nuisance in the rare cases when they escape from various research facilities.