In terms of overall acting, I give it to The Shining. Nicholson's performance in the movie was pretty chilling and the overall setting of the movie had a claustrophobic aura about it, despite the size of the hotel. At the same time, however, I thought Robert Shaw's performance as Quint was fantastic in Jaws. Personally, I think the man should've gotten an Oscar nomination for his performance. The character Quint was someone that was very likable and kind of hateful at the same time. It was a pain in the ass to work with the man but he seemed like he'd be the life of the party at a bar or something.
The Shining is arguably the best film adaptation of a horror novel ever made. Some film adaptations of Stephen King books have been downright shitty, which some of the books have been as well, but The Shining worked. It seems pretty tame by today's horror standards, but The Shining was a great example of storytelling and that more than made up for any lack of gore. Jaws is the father of the modern summer blockbuster. Jaws tapped into a primal fear that a lot of people never really gave any thought to before. Unintentionally, it sort of made all sharks public enemy #1 in the minds of a lot of people. I know people today that won't go into the ocean, even on a boat, because of seeing the first Jaws movie when they were younger.
As far as the better overall film, I have to go with The Shining. For the most impactful & influential film, that easily goes to Jaws here.