For as long as I've been writing, there's been plenty of debate among writers about what's more important: character or plot.
Obviously enough, the two can't be completely separated – there's no plot without characters' actions, and characters can't grow or develop without a plot.
But many stories will
come down more heavily on one side than the other. In thrillers or adventure stories, for instance, the plot is generally the most important thing – the reader wants to find out what happens next, or wants to learn the solution to a particular mystery. In, say, romance novels, there might not be much action – but the story is driven onwards by the "will they or won't they?" tension.
As a reader, I love characters first and foremost. I get a bit lost in books (and TV series!) with fiendishly complex plots – but I love characters who are interesting, flawed, complex people. When I read more plot-centric genres, I tend to gravitate towards the more character-rich end of those (e.g. with thrillers, I read mostly psychological and domestic thrillers, by authors
like Sophie Hannah and Liane Moriarty).
So as a writer, I'm a bit biased. :) I think characters matter a bit more than plot, because if your novel's characters are flat or unconvincing, no-one's going to get far enough to discover your intricate plot.
You might feel differently, though! Maybe you want your characters to be fairly engaging, but what really hooks you and keeps you reading is the plot.
Or maybe
there's something else that matters even more to you. If you enjoy literary fiction, you might be interested primarily in reading beautifully put-together prose ... and you don't mind if the characters and plot aren't especially developed.
So there's no one "right" answer
here. Instead – figure out what matters most to you in what you read, and think about ways to bring that into what you write.