When asked at convention panels which is more important, I steal a line from Bob McKee and answer, “Plot is character.” That is, the choices a character makes both determine the plot and reveal personality. At least, that’s the way most of us try to make it work.
Yet still people ask the question, and I have to acknowledge that some readers seem to respond more to what happens while others seem more concerned with relationships and character evolution.
Do you follow series (or authors) more because of their interesting plots or because of the characters you expect from them? If it’s plot, what makes a great plot for you? If it’s character, what qualities attract you to your favorite fictional characters?