I asked that question on my Facebook fan page several mkonths ago. Both are elements required for good fiction; I was just curious which one other writers preferred.
On closer study – this will come as no surprise to people who know me – plot is the more essential of the two.
Characters are definitely important – distinctive, memorable ones. Stock, cardboard ones just lie there, are easily forgotten and usually contribute to a story or novel not even being picked.
Plot is needed even more. It drives a story from point A to point B… without one a story just wanders aimlessly. A story can begin from memorable characters; as soon as they do something (anything) those actions become plot.
As such the two are intertwined.