I read a lot. Well, it seems like a lot. About 100 books a year, plus or minus, depending on how many repeats there are in the year. So, I am ALWAYS looking for recommendations. Last night at a restaurant, the server recommended "Beneath a Marble Sky" and I immediately bought it on my Kindle. (And, for me, Kindle has saved my back. In the old day when I used to have to save a lot of space in my luggage for all the books was a total pain in the lower back.)
I rank my books by category, since comparing Linda Howard with David Baldacci seems unfair. So...
In the sort of science fiction category, I think Neal Stephenson wins. I think he wrote the best book of the 20th century (Cryptonomicon), an I loved Seven Eves. I did get tired through the Baroque Cycle though.
In the Romance category, Linda Howard by a mile. Even though they may all have the same plot, I have yet to read one of hers that did not thrill me. Or swoon me...
In the Popular category, it's hard to beat Michael Connelly.
In the Police procedural, I still think Sue Grafton is the Queen.
In the LitFic category, there are a ton of great options, such as Kite Runner, All the Light We Cannot See, etc
In the make you cry category, there are many contenders, but if you are a teacher, or know a teacher, "Ms. Bixby's Last Day" will make you cry forever...
Bad Ass Protagonist? No question. Jack Reacher from Lee Child. He would kick Kirk McGarvey's ass...
For total fun, read them when there is nothing new: I often go back to the Harry Potter series, and even Twilight. (Sorry. I just put all my opinions in jeopardy, didn't I?)
Transgender novel? Although it gives away a lot probably, Conclave, since Harris is a popular author...
Literally, I could go on for hours...

Edit: I gave my vote for the best book of the 20th Century. My vote for the best book of the 21st Century, so far? 11-22-63 from Stephen King...