"What do you consider the most important in a story: the plot or the characters?"
Man, this is an easy question to answer, because I always look for great characters in a story. Before anything else, I really love being able to connect to the main players. If I can't, then the plot doesn't quite interest or thrill me the way it otherwise could. I love serials, and it's because I am constantly falling in love with characters and can't bear the thought of leaving them alone after only one book.
Now, whether plot or characters are more essential to the success of a book is a different way to view the question. And to that I have no answer. I can forgive a book an average plot...but if the characters are duds, I tend to drag my feet reading about them. And that's not to say I need to agree with a character... I've gotten attached to some antagonists (the whole "love to hate" deal), too. But they have to intrigue!
Some authors that I think create fabulous characters include Victoria Dahl, Laurell K. Hamilton (for their detail and intricacies), and Janet Evanovich.
So there you have it! What about you...I'm curious to know! ^_^