Why do we watch films? Well, it depends on who you are. You can watch them for their incredible VFX, or their gripping story. Out of the Oscar nominees for VFX, that I’ve seen, I can say that they have incredible VFX & Story. For example, Interstellar. The story had me gripped, and quite honestly blown away, for the entire film. The VFX had exactly the same effect on me. So deciding which is more important is difficult. Without either aspect, I would not have enjoyed the film.
I believe it also comes down the genre. Action/Adventure & Fantasy/Sci-Fi films primarily need to trade off story for a little more VFX. This is how they grab their target audience, large explosions and breathtaking visuals. Whereas films driven by story, for example The Imitation Game, use their plot to draw in their target audience. The Imitation Game didn’t require VFX, but what it did require was a well written screenplay. This is how I feel genre effects the answer to this question.
There will always be an audience of those who don’t mind the trade off between story & VFX, whichever way it goes.
From the perspective of a business owner, who wants to sell as many units or tickets or DVD’s as possible, then I would speculate that VFX is more important. The trailers with the big explosions draw in more people. More people means more money.