While Jaws does have a good story and characters, I think The Terminator is a better film, even though it does have a similar story to Jaws. Both Jaws and The Terminator are based more upon their villains than the heroes of the stories, with the main cast composed of a few, well written characters.
While Jaws does have a powerful villain, there is the ability for the town to avoid the villain by simply preventing access to the beach which the shark frequents. With The Terminator though, there is no avoiding the villain as he will not stop hunting his target until he completes his mission. I think the higher stakes of The Terminator make it a more interesting and thrilling movie, with Jaws being a simpler and less intense movie.
I also prefer Terminator 1 to Terminator 2, as 2 is called Judgement Day but doesn't have a strong enough connection to Judgement Day to justify its name. I think it would have been easier to just to name it Terminator 2, without the byline, to be honest.