Let’s see …
In grade school I read a lot of age-appropriate “general fiction” - usually mild “adventure” stories featuring a young boy protagonist. I was a big fan of stuff like the Henry Huggins books, Encyclopedia Brown, and what have you.
By junior high I had discovered science fiction, and read almost nothing but sci-fi all the way through high school (disregarding “required reading for school” crap like Wuthering Heights, The Great Gatsby, and that dreadful book about all the boys killing each other on an island somewhere, the name of which escapes me. Wait … oh yeah, The Lord of the Flies. Shudder.) In particular, I discovered Asimov, and by the time I finished high school in 1984 I had read probably 90% of the fiction he’d written up to that point.
Thanks to a solitary semester at college where I discovered the joy of private investigator TV shows like Mike Hammer, I mostly abandoned sci-fi and for a few years devoured mysteries. I found a handful of wonderful, prolific authors like Lawrence Block (the Bernie Rhodenbarr “Burglar” novels), H.R.F. Keating (Inspector Ghote), and Georges Simenon (Inspector Maigret) and read everything by them I could get my hands on. That lasted for a few years.
Through my 20s I did more drinking than reading, but I managed a good mix of mysteries, science fiction, and pulp action/adventure novels (like Mack Bolan’s The Executioner books). Also lots of Star Wars and Star Trek novels, as well as novels set in the Shadowrun roleplaying game universe.
In my early 30s I surprised myself by discovering that I enjoyed historical fiction, particularly when set in “ancient history”. I read a bunch of W. Michael Gear & Kathleen O’Neal Gear’s “The First North Americans” books. Another good find was Peter Danielson’s Children of the Lion, a series of well over 20 books set in the Biblical Old Testament times. The series basically retold most of the historical portions of the Old Testament, but from the point of view of a family of non-Hebrew blacksmiths who interacted with the Hebrews/Israelites through the generations. (Somewhat amusing side note on this series: I inadvertently stumbled upon a plagiarist on the Web. Some guy had posted, online, what he claimed was his own original novel, called “Children of the Lynx”. I started reading, and within a few paragraphs it was sounding awfully familiar. I grabbed my copy of Children of the Lion and started comparing. The “Lynx” story was a word-for-word copy, except the guy had apparently transcribed the entire book into his word processor and then used search & replace to change “Lion” to “Lynx” and to change all the character names and city names. He was partway through the third novel in the series when I found him. Giving him the benefit of the doubt by assuming he must be some dumb high school or college kid, I dropped him an e-mail and suggested he knock that shit off before the original author and/or publisher caught him at it. Within a couple days the whole thing was gone from his Web site.)
In my mid-to-late 30s I got into fantasy in a big way, mostly through discovering Piers Anthony. I’m still mostly reading fantasy these days, with the occasional sci-fi book thrown in for variety. Over the last couple of years, I’ve been reading Dungeons & Dragons novels almost exclusively, mostly the Dragonlance and Eberron books (and also a couple of Forgotten Realms trilogies).
The one consistent thing I’ve noticed in my reading patterns, going all the way back to grade school and regardless of genre, is that I’m a big fan of ongoing series and authors whose novels are all set in the same fictional universe (this extends to multiple authors writing in a shared universe). I think what I really like is being able to get to know a particular character in-depth, in a way that you can’t get from just a single novel, and exploring a particular world over the course of many novels.