If I had to chose between gore and plot for instance I'd probably go for plot, once you've seen one guy with a testicle popped open you've seen them all, but it's the manner that leads up to this mutilation and the suspense surronding it that makes a great film. Like the Hostile movies for example.
Blockbuster films such as Rambo and Watchmen use gore as a gimmick, but when it's done right it can be fucking fantastic.