Agree with the general assessment that they're both amazing. Agree with the people who are saying that Alien edges it, although it's hard to really say that either of them are "worse than the other" because they're so amazingly different in their nature.

Also, regarding the intellect of the alien, they are very smart at being dangerous killers, but that doesn't mean it's suddenly surprising that they can be beaten by humans. I would still say that the humans are smarter overall. It's like being put into a cage with a large number of dangerous animals. The animals can kill the humans but that doesn't mean they're smarter than humans. Strength comes into play. The exoskeleton is still a creature I would say is smarter than your average animal, particularly when it comes to strategy, but I wouldn't put them on Predator/Human level of intelligence.

Also, Forsaken, you criticise the alien intelligence in your first post for throwing large numbers of aliens into the fray to get taken down by sentry guns and then stopping when they run out of bullets. However, it should be noted that the aliens didn't know the bullets had run out (I believe there were something like four bullets left? xD). Also, compare the situation to humans. How many times would an army charge into battle just to get massacred? These things do happen. Likewise, a single human can take down multiple other humans. It's not unusual to suggest that one alien can differ from the many aliens in a similar way.