While most writers will eventually have to make a choice between character or plot as their central focus in a piece, that does not mean the decision is (or should be) an exact either/or. While one may prevail as the leading force of the story, that does not mean the other should be sacrificed. The best stories will have both an enticing plot and complex, believable characters. A writer could create the most dynamic and entertaining cast of characters in the world, but the reader will get bored if those characters never do anything. Likewise, the author could craft a thrilling emotional roller coaster of a plot, but the reader will have difficulty investing if she cannot bring herself to care about the characters. That being said, the most important thing to keep in mind about this question is that the answer will vary from writer to writer and from story to story. Whether you choose to focus more on plot or on the character will depend on your intentions for the reader and for the story itself.
In her book Writing Irresistible Kidlit, Mary Kole explains that a plot-centered story is more likely to fall under the category of commercial fiction, while a character-centered story will more likely be literary fiction. In other words, when choosing to focus on the plot, the writer is more likely to produce a piece that serves the purpose of entertainment and escapism. When choosing to focus on character, the writer is more likely to produce a piece that serves the purpose of educating or teaching a moral lesson, as in a coming-of-age story. The decision between the two, then, depends in part on what the author wants the reader to get out of the story.
A further consideration is the story itself. As you begin developing your idea, think about whether the focus revolves around a lesson that your character learns or a pivotal event that changes the circumstances of the fictional world you’ve created. This will determine whether you should focus more on developing your character or plot, respectively. After you’ve determined which will be more central to your story, you are ready to begin developing both aspects more thoroughly. If you’ve chosen to think about character, ask yourself what your characters main motives and objectives are and what obstacles you can create for them with your plot. If you’ve chosen to focus on plot, ask how the plot interacts with your characters’ lives and how they will respond. These preliminary questions will help you to develop your plot and character together, no matter which one becomes your main focus.