I've read thousands of books in the 43+ years that I've been reading. There are a few dozen books that I've read multiple times, but the majority of the titles that have passed through my hands and my brain were distinct.
I read a lot of different genres: fantasy, science fiction, procedurals, historical mysteries, historical romances, chick lit, thrillers, histories, memoirs, science, design, art, fitness, poetry. I'll read the back of the cereal box if that's all that is available.
I've read every original-series Star Trek novel, all of the Dragonriders stories, all of the Tarzan stories, all of the Sherlock Holmes stories, most of Jane Austen, all of Frances Burney, all of Tom Robbins, all of Dick Francis and Ngaio Marsh and Laurie R. King and J.D. Robb. I've read Wells and Heinlein and Bradbury and Bester and Chalker and I've made a dent in Scalzi. I've read Kelly and Putney and Balogh and Veryan and Heyer and Butler and Carlyle. I've read chunks of Shakespeare and Marlowe and Chaucer and even Milton.
With all of this, there are still thousands - millions - of books that I haven't read and will never read. No one can read everything. What we choose to read is very much a matter of personal taste.
I had all of Andrew Vachss' books at one point. His are probably among the darkest and most violent books I've read. I found him at a rather low point and I appreciated his uncompromising approach; in a way, he is the most moralistic writer I've ever wallowed in. As an attorney specializing in juvenile justice and child-abuse cases, this guy was steeped in rage of a very pungent nature. He let it all out in those books. The mystery/thrillers I prefer now tend to be gentler, but like most in the genre, they are about solving a crime or repairing an injustice. They are fix-it stories, as are romances.
There are entire shelves of the bookstore (virtual and IRL) that I pass by. I don't read much self-help or commentary. I don't read "horror" - unless you count Carrie Vaughn's Kitty the Werewolf series. I don't read a lot of modern romances, though I adore Jill Mansell.
That said, most of my favorite genre writers do leaven their stories generously with romance. It's only the second most important thing in most of our lives, after all.
I like fiction, even that set in imaginary worlds, to feature characters that I can relate to as a modern urban professional. I am not so good with small-town settings, as they all too often revolve around gossip and cronyism, and generally reinforce my own small-town experience of conformity and repression. This is one reason I don't read many Regency romances any more.
As to dialogue, I like characters to speak in a way that's appropriate to their context. Not all people talk the same way. A writer should make the speech as clear as possible, without making everybody sound the same, or (worse) sound like the writer's idea of his/her target reader. Dick Francis was brilliant at this.
I like plenty of action, too. There is the occasional book in which nothing really happens that I love in spite of that. But generally speaking, I want the characters to get up and do something. Whether it's running a flower shop or making a movie or solving a murder, I want the characters to be out in the world, not sitting at home ruminating.
I pass by most "literary" fiction for this reason. I don't want a novel that's really the writer's commentary on some tragedy of his/her own life, or on modern society. The story needs to have its own driver. Just because there are only seven plots (or whatever the "truism" says) is no reason to not invent a set of characters who can act out one of those plots in a new and entertaining way.
What is the point of this particular essay, you may ask? Well, as some of my friends know, I've been on a writing binge lately. And my writing proceeds directly, as an apple from a tree, from what I've read.
I'm a critical reader. Not in the sense of "looking for something to complain about" but in the sense of figuring out how a writer achieved an effect, and thinking about whether it served the story, how to apply the same technique in something of my own, and whether it's worth trying given the context of what I'm doing.
The going-on-five years of this blog have been excellent exercise in regularly turning out hundreds of words. I'm not sure what really kicked away the rock that had dammed up my writing urge before last summer, or what that rock consisted of. But for whatever reason, things are flowing and it's kind of fun.