I've always thought of Predator as an Aliens rip-off. Equipping each soldier with a helmet cam was a great idea. It served the purpose of identifying each individual, while also providing point of view vantage points to bring the audience closer to the conflict ... but it was James Cameron's idea, that the Predator filmmakers shamelessly stole.
Gotta go with Aliens ... in a big way on this one. Also, with Cameron's close relationship with Arnold, I feel like an opportunity was missed. Why didn't Arnold play Hicks (instead of the bland Michael Biehn) in Aliens? Then, Predator wouldn't have even been necessary.