So, as one grows and (ahem) matures, ones tastes change.
Also as I get older, it gets harder to have a "favorite" book, as my personal literary constellation fills up.
When a kid, I had a favorite book (though it changed as time went by) Now, I have 20 or so favorite books. Of course one drawback, is some of them I've read so many times despite being a "favorite" they can be kind of stale, until they lie fallow for a few years.
So, my "Oh my god, this is my favorite book" as a kid (as best as I can reconstruct).
- 4th grade: The Secret of the Martian Moons (Donald Wollheim). First SF book read, so by default my favorite
- 4th grade: A Princess of Mars (Edgar Rice Burroughs)
- 5th grade: The Mightiest Machine (John W. Campbell)
- 6th grade: Prince of Peril (Otis Adelbert Kline)
- 6th grade: Time for the Stars (Robert Heinlein)
- 7th grade: Starship Troopers (Robert Heinlein)
An interesting thing is as I matured my literary tastes went from pre world war 1, to the pre golden age '30's and on to the 60's.
That being said, Science Fiction books that I can read again and again and again (off the top of my head):
- Shards of Honor -- Louis McMaster Bujold
- The Curse of Chalion -- Louis McMaster Bujold
- Beyond the Green Star -- Lin Carter
- Rendouvous with Rama -- Arthur C. Clarke
- Bill, the Galactic Hero -- Harry Harrison
- The Stainless Steel Rat -- Harry Harrison
- The Stainless Steel Rat's Revenge -- Harry Harrison
- The Stainless Steel Rat saves the world -- Harry Harrison
- Citizen of the Galaxy -- Robert Heinlein
- The Puppet Masters -- Robert Heinlein
- Starman Jones -- Robert Heinlein
- Tunnel in the sky -- Robert Heinlein
- The Door into summer -- Robert Heinlein
- Stranger in a strange land -- Robert Heinlein
- Catastrophe Planet -- Keith Laumer
- A Plague of Demons -- Keith Laumer
- The Time Travellers Wife -- Audrey Niffenegger
- The Tommyknockers -- Stephen King
- The Witches of Karres -- James H. Schmitz
- Lallia -- E. C. Tubb
- Slan -- A. E. Van Vogt
- The Weapon Shops of Isher-- A. E. Van Vogt
- The Time Machine -- H. G. Wells
- Darker than you think -- Jack Williamson
- The Amber series -- Roger Zelazny
This leaves out someone like the tragic Stanley Weinbaum, who I'd include mostly due to his short stories.
So, anyway, what was your first favorite science fiction book, or the first SF book you've read, and how did your tastes change/evolve?